CSLB Landscaping (C-27) Trade — All Questions

A soil that drains very quickly, warms fast, and holds little water is MOST likely which texture?

• a.Sandy soil✓
• b.Silt
• c.Peat
• d.Clay

Sandy soils have large particles with large pore spaces, so water drains through rapidly and little is retained. They warm quickly in spring but dry out fast and need more frequent irrigation. Adding organic matter improves their water and nutrient holding capacity.

Most landscape and turf plants grow best in soil with a pH in which range?

• a.About 3.0 to 4.0 (strongly acidic)
• b.About 9.0 to 10.0 (strongly alkaline)
• c.Exactly 8.5 in all landscape soils
• d.About 6.0 to 7.0 (slightly acidic)✓

A slightly acidic to neutral pH of roughly 6.0 to 7.0 keeps most nutrients available for uptake by common landscape plants and turf. Extremely acidic or alkaline soils lock up nutrients even when they are present. Acid-loving plants like azaleas prefer the lower end of this range.

To lower the pH of an alkaline soil, which amendment is commonly used?

• a.Agricultural lime
• b.Elemental sulfur✓
• c.Gypsum for pH change
• d.Wood ash

Elemental sulfur is oxidized by soil bacteria into sulfuric acid, gradually lowering soil pH over weeks to months. Lime and wood ash raise pH, and gypsum changes soil structure and adds calcium without significantly changing pH. Sulfur is the standard choice to acidify alkaline soils.

In a fertilizer labeled 16-6-8, the three numbers represent the percentage of which nutrients in order?

• a.Phosphorus, nitrogen, potassium
• b.Potassium, phosphorus, nitrogen
• c.Nitrogen, phosphorus, potassium✓
• d.Nitrogen, potassium, phosphorus

The three-number N-P-K label always lists nitrogen first, phosphorus (as P2O5) second, and potassium (as K2O) third. So 16-6-8 is 16 percent nitrogen, 6 percent phosphorus, and 8 percent potassium by weight. Nitrogen drives leafy green growth, phosphorus supports roots and flowers, and potassium aids overall vigor.

A 50-pound bag of 20-0-10 fertilizer contains how many pounds of actual nitrogen?

• a.1 pound
• b.20 pounds
• c.5 pounds
• d.10 pounds✓

Actual nitrogen equals the bag weight times the nitrogen percentage, so 50 pounds times 0.20 equals 10 pounds of nitrogen. Landscapers use this calculation to apply the correct pounds of nitrogen per 1,000 square feet. Knowing actual nutrient content prevents over- or under-application.

Applying a 3-inch layer of organic mulch around plants primarily provides what benefits?

• a.It increases soil compaction around the roots
• b.It eliminates all irrigation needs
• c.It conserves moisture and suppresses weeds✓
• d.It raises soil pH sharply within days

A layer of organic mulch reduces evaporation, keeps soil temperatures more stable, and blocks light that weed seeds need to germinate. As it decomposes it also adds organic matter to the soil. Mulch is one of the most cost-effective water-saving practices in landscaping.

When planting a container-grown shrub, the top of the root ball should be placed at what level relative to the surrounding soil?

• a.6 inches below grade
• b.Buried under 4 inches of soil over the crown
• c.At or slightly above the surrounding grade✓
• d.12 inches below grade

The top of the root ball should sit at or slightly above finished grade so the crown does not sit in water and settle too deeply. Planting too deep suffocates roots and can rot the crown or trunk. Slightly high planting allows for minor settling while keeping the crown dry.

Gypsum is added to certain clay soils primarily to accomplish what?

• a.It lowers the soil pH significantly
• b.It kills weed seeds already in the bed
• c.It displaces sodium and improves structure✓
• d.It adds a large amount of nitrogen

Gypsum, calcium sulfate, supplies calcium that replaces sodium in sodic clay soils, improving aggregation and water penetration. It changes soil structure and drainage without appreciably altering pH. It is not a fertilizer and does not add nitrogen.

A newly planted tree needs staking. What is the correct staking practice?

• a.Wrap wire tightly around the bark
• b.Allow movement and remove stakes in a year✓
• c.Tie the trunk rigidly for at least five years
• d.Drive one stake straight through the root ball

Stakes should support the tree while allowing slight trunk movement, which encourages a stronger trunk and root system. Ties should be loose and use a broad, soft material, and stakes are typically removed after about one growing season. Rigid staking and bare wire damage the tree and create a weak, dependent trunk.

Which practice BEST improves drainage in a heavy clay planting bed?

• a.Compact the soil before planting
• b.Line the bottom of the bed with plastic sheeting
• c.Add fine sand only in small amounts
• d.Incorporate organic matter such as compost and improve grading✓

Blending compost and other organic matter into clay improves aggregation, creating larger pore spaces that let water move through. Combined with grading that directs excess water away, this relieves waterlogging. A small amount of sand can actually make clay worse by forming a concrete-like mix, and plastic traps water.

Proper plant spacing at installation should be based on what?

• a.The size of the nursery container only
• b.Fitting as many plants as possible
• c.The mature size and spread of the plant✓
• d.The current size of the plant

Plants should be spaced according to their expected mature width so they fill in without overcrowding. Spacing based on current small size leads to crowding, poor air circulation, and disease as plants grow. Good spacing reduces long-term maintenance and pruning.

A soil amendment high in nitrogen but low in decomposition, like fresh wood chips tilled into soil, can cause what short-term problem?

• a.A large and rapid rise in soil pH
• b.Temporary nitrogen deficiency, or drawdown✓
• c.Excess nitrogen that burns the plants
• d.Immediate salt toxicity in the root zone

When high-carbon materials like fresh wood chips are mixed into soil, microbes decomposing them consume available nitrogen, temporarily starving plants of it. This nitrogen drawdown causes yellowing until decomposition slows. Using wood chips as surface mulch instead of tilling them in avoids the problem.

Cool-season turfgrasses such as tall fescue grow most actively in which conditions?

• a.Deep winter freezes only
• b.Cooler spring and fall temperatures✓
• c.Complete shade year round
• d.The hottest summer weeks

Cool-season grasses like tall fescue peak in growth during the cooler temperatures of spring and fall and slow down in summer heat. Warm-season grasses such as Bermuda are the opposite, thriving in summer. Choosing the right type for the climate reduces water and maintenance needs.

When establishing turf from seed, keeping the seedbed consistently moist is important because what?

• a.Water is needed only after sprouts appear
• b.Seeds germinate better when completely dry
• c.Germinating seeds and shallow roots die quickly✓
• d.Moisture prevents any weed growth at all

Germinating seeds and their tiny first roots sit near the surface and die rapidly if the seedbed dries out. Light, frequent watering keeps the top layer moist until seedlings establish deeper roots. Once established, watering shifts to deeper and less frequent cycles.

Rough grading followed by finish grading before planting is done primarily to accomplish what?

• a.To create low spots that hold water
• b.To increase soil compaction before planting
• c.To set surface drainage and a smooth planting bed✓
• d.To remove all topsoil from the site

Grading shapes the soil surface so water drains away from structures and toward intended outlets, and finish grading creates a smooth, even bed for planting or turf. Poor grading causes ponding, erosion, and drainage complaints. Positive slope away from buildings is a core goal.

Compost is added to soil primarily to do what?

• a.To improve structure and add organic matter✓
• b.To compact the soil around new plants
• c.To serve as the only nutrient source
• d.To raise pH to strongly alkaline levels

Compost improves soil structure, increases water and nutrient holding capacity, and feeds beneficial soil microorganisms. While it adds some nutrients, its main value is as an organic amendment that improves overall soil health. It benefits both sandy and clay soils.

Which plant selection strategy BEST supports water-efficient landscaping in California?

• a.Drought-tolerant plants grouped by water need✓
• b.Mixing high- and low-water plants on one valve
• c.Select plants at random from the nursery
• d.Plant only high-water tropical species

Selecting drought-tolerant, climate-appropriate plants and grouping them by similar water needs, called hydrozoning, lets each irrigation zone be scheduled efficiently. Mixing high- and low-water plants on one valve forces overwatering of the low-water plants. Hydrozoning is a core MWELO efficiency practice.

A soil test reports very low phosphorus. Which fertilizer analysis would BEST correct it?

• a.21-0-0
• b.46-0-0
• c.0-0-60
• d.0-45-0✓

The middle number of the N-P-K label is phosphorus, so 0-45-0 supplies a high level of phosphorus and nothing else. 21-0-0 and 46-0-0 supply only nitrogen, and 0-0-60 supplies only potassium. Matching the deficient nutrient to the fertilizer analysis avoids waste.

Balled-and-burlapped (B&B) trees should have synthetic burlap and wire baskets handled how at planting?

• a.Removed only after two full growing seasons
• b.Left fully intact around the entire root ball
• c.Never touched once the tree is set
• d.Loosened and folded down, synthetics removed✓

Natural burlap decomposes, but synthetic burlap and twine do not and can girdle roots, so they should be removed or at least peeled back from the top of the root ball. Wire baskets are cut and folded down after the tree is set. This lets roots grow outward into the surrounding soil.

Slow-release (controlled-release) fertilizers are advantageous because they do what?

• a.They release all their nutrients in one day
• b.They contain no nitrogen or potassium
• c.They feed gradually, cutting burn and leaching✓
• d.They only work below freezing temperatures

Controlled-release fertilizers meter nutrients out over weeks or months, lowering the risk of fertilizer burn and reducing nutrient leaching into groundwater. This gives steadier plant growth and fewer applications. They are especially useful for sandy soils where quick-release nutrients leach fast.

The planting hole for a balled tree should generally be dug how wide relative to the root ball?

• a.Ten times the width and twice as deep
• b.The same width but twice as deep as the ball
• c.Two to three times the width of the ball✓
• d.Half the width of the root ball

A hole two to three times as wide as the root ball loosens surrounding soil so new roots spread outward easily, while keeping depth equal to the ball prevents settling and deep planting. Digging deeper than the ball causes the tree to sink and the crown to sit too low. Wide and shallow is the standard rule.

Salt buildup in soil from irrigation water or fertilizer is BEST managed by what practice?

• a.Deep irrigation to leach salts downward✓
• b.Adding more fertilizer to the planting bed
• c.Compacting the soil surface very firmly
• d.Reducing all watering to zero for a month

Applying a deep, thorough irrigation, called leaching, dissolves accumulated salts and carries them downward below the root zone where they no longer harm plants. This requires soil with adequate drainage. Adding more fertilizer would worsen the salt problem.

A soil report lists 45 percent sand, 35 percent silt, and 20 percent clay. What texture class is that, and what does it mean for irrigation?

• a.Clay loam, which requires frequent shallow irrigation cycles
• b.Silt loam, which holds the most water of any texture class
• c.Loam, which holds moderate moisture and drains at a moderate rate✓
• d.Sandy clay, which drains slowly and needs long soak periods

That mix falls in the loam class, the balanced texture that both retains usable moisture and drains at a workable rate. Sandy clay would need far more clay. Silt loam would need silt to dominate, and even then peats and organic soils hold more water. Clay loam is heavier than these percentages describe and is not watered by frequent shallow cycles.

Two beds are irrigated identically, one in sand and one in clay loam. Why does the sand bed need water more often?

• a.Sand transmits more water upward to the leaf canopy
• b.Sand loses more water to evaporation from the surface
• c.Sand has a higher permanent wilting point than clay loam
• d.Sand holds less available water per foot of soil depth✓

Large pores drain quickly and hold little water against gravity, so sand stores far less plant-available water per foot of depth and empties sooner. Surface evaporation is similar for both when mulched. Clay actually has the higher wilting point because it holds water too tightly to release. Soils do not transmit water to the canopy; roots and the plant do.

A percolation test in a proposed tree pit shows water standing in the hole 24 hours after filling. What does the installer conclude?

• a.The pit should be dug wider so more surface area is exposed
• b.The pit needs additional organic amendment mixed into the backfill
• c.Drainage is inadequate and the planting detail must be changed✓
• d.The soil is within the normal range for a clay site

Water standing a full day means the pit will hold the root ball in saturated soil, so the detail must change, whether by mounding, subdrainage, or moving the tree. Amending backfill in a poorly draining hole creates a bathtub that fills faster. Widening the hole does not give the water anywhere to go. A full day of standing water is a failure, not a normal clay result.

A landscape is failing in a heavy clay pad that was compacted by grading equipment. Which corrective measure addresses the root cause?

• a.Increasing irrigation frequency to keep the surface moist
• b.Ripping the compacted layer and incorporating organic matter✓
• c.Top-dressing with two inches of sand across the pad
• d.Applying a complete fertilizer at twice the label rate

Compaction destroys pore space, so roots and water cannot move, and breaking that layer and blending in organic matter restores structure. Extra fertilizer does not create pore space and can burn stressed roots. More frequent watering keeps a compacted soil saturated. A thin sand layer over clay creates a perched water table rather than drainage.

A soil test returns a pH of 8.1 on a site where azaleas are specified. What is the most practical response?

• a.Apply agricultural lime to buffer the soil before planting
• b.Plant as drawn and correct the pH with monthly acid rinses
• c.Revise the plant list toward species tolerant of alkaline soil✓
• d.Increase the phosphorus rate to offset the high pH

Sustained pH change on an alkaline California soil is slow, expensive, and prone to rebound, so matching the plants to the site is the durable answer. Lime raises pH and would make the problem worse. Extra phosphorus does not change pH and can tie up other nutrients. Monthly acid applications are a maintenance burden that rarely holds.

Which amendment is used to lower the pH of an alkaline landscape soil over time?

• a.Wood ash spread evenly and watered in
• b.Elemental sulfur, which soil bacteria convert to acid✓
• c.Dolomitic limestone worked into the top six inches
• d.Calcium carbonate blended with the backfill

Soil bacteria oxidize elemental sulfur into sulfuric acid, which is the standard way to move pH downward. Dolomitic limestone and calcium carbonate are liming materials that raise pH. Wood ash is strongly alkaline and raises pH as well, so three of these four choices move the soil in the wrong direction.

Newly emerging leaves on a citrus tree are yellow between green veins while older leaves stay dark green. What does this pattern suggest?

• a.Nitrogen deficiency, which appears first on new growth
• b.Phosphorus deficiency from cold soil temperatures
• c.Iron deficiency, common where soil pH is high✓
• d.Potassium deficiency caused by excess irrigation

Iron is immobile in the plant, so a shortage shows on the newest leaves as interveinal chlorosis, and it is common on alkaline California soils where iron is present but unavailable. Nitrogen is mobile and yellows the oldest leaves first and uniformly. Potassium shortage shows as marginal scorch on older leaves. Phosphorus shortage typically shows as dull purpling.

A 50-pound bag is labeled 15-5-10. How much actual nitrogen does the bag contain?

• a.1.5 pounds
• b.3.0 pounds
• c.7.5 pounds✓
• d.5.0 pounds

The first number is percent nitrogen by weight, so 15 percent of 50 pounds is 7.5 pounds. The 1.5-pound figure would come from a 3 percent product. Three pounds would come from a 6 percent product. Five pounds is the phosphate content of this bag expressed the same way, which is a common mix-up.

A specification calls for one pound of actual nitrogen per 1,000 square feet using a 20-0-10 fertilizer. How much product is applied per 1,000 square feet?

• a.10 pounds
• b.20 pounds
• c.2 pounds
• d.5 pounds✓

Dividing the pound of nitrogen wanted by the decimal fraction of nitrogen in the product gives 1 divided by 0.20, or 5 pounds of product. Ten pounds would deliver two pounds of nitrogen. Twenty pounds would deliver four pounds and risk burning. Two pounds delivers only four tenths of a pound and falls short of the specification.

An owner asks why the crew uses a controlled-release fertilizer on a slope above a creek instead of a soluble product.

• a.It contains more total nutrient per bag and covers more ground
• b.It changes soil pH less than soluble products do
• c.It releases gradually, lowering burn risk and leaching✓
• d.It costs less per pound of nitrogen than soluble fertilizer

A coated or slow-release product meters nutrient out over weeks, so less is available to wash off in a storm and less is present at any moment to burn roots, which matters directly above a waterway. Analysis per bag is usually lower rather than higher. Both types can affect pH depending on nitrogen source, and slow-release costs more per pound of nitrogen.

Fresh wood chips are tilled into a planting bed and the plants yellow within weeks. What happened?

• a.The chips held water and drowned the shallow feeder roots
• b.The chips raised soil pH beyond the range the plants tolerate
• c.The chips released natural herbicides that damaged the roots
• d.Microbes decomposing the chips tied up available soil nitrogen✓

High-carbon material incorporated into soil feeds a microbial bloom that immobilizes nitrogen while it decomposes, and the plants go hungry until the process finishes. Wood chips do not shift pH sharply. Allelopathic effects are limited to a few species and not the general case. Chips tilled in improve aeration rather than causing saturation.

How should the same wood chips be used so that nitrogen tie-up is not a problem?

• a.Left on the surface as mulch rather than incorporated✓
• b.Composted for two weeks and then tilled in at six inches
• c.Applied with a high-phosphorus starter fertilizer at planting
• d.Blended at no more than ten percent by volume into backfill

Tie-up happens where carbon and soil are mixed, so leaving chips on top confines the effect to a thin surface layer while the mulch still suppresses weeds and holds moisture. Two weeks is not enough composting. Even ten percent by volume still incorporates raw carbon. Phosphorus does not substitute for the nitrogen the microbes take.

What does MWELO require of a project regarding soil before the planting plan is finalized?

• a.A geotechnical report establishing the bearing capacity of the subgrade
• b.A record of the last three crops or land uses on the parcel
• c.A soil management report with testing and amendment recommendations✓
• d.A certified laboratory analysis of the irrigation water source

MWELO requires a soil management report so that amendment and mulching decisions are based on actual soil chemistry and texture rather than habit. Water quality analysis is useful but is not the required report. Bearing capacity belongs to structural design. Prior cropping history is not part of the ordinance.CA MWELO (Title 23)

MWELO sets a minimum mulch depth on exposed soil in planting areas. Which statement matches the requirement?

• a.Two inches, applied everywhere including turf areas
• b.Four inches, with the layer piled against trunks to hold moisture
• c.At least three inches, with turf and creeping groundcover excepted✓
• d.One inch, refreshed each time the landscape is fertilized

The ordinance calls for a minimum three-inch layer on exposed soil in planting areas and recognizes that turf, rooting groundcover, and direct-seeded areas cannot be mulched that way. Two inches falls short of the minimum. Four inches piled against trunks invites collar rot. One inch neither suppresses weeds nor conserves moisture.CA MWELO (Title 23)

Why must organic mulch be pulled back from the trunk of a newly planted tree?

• a.Mulch against the trunk prevents the root flare from taking up nitrogen
• b.Constant moisture against the bark encourages crown and collar rot✓
• c.Mulch against the trunk raises the soil pH in the root ball
• d.Mulch against the trunk attracts beneficial insects away from the canopy

Bark is not built to stay wet, and mulch heaped against it holds moisture that leads to collar rot and encourages rodents and adventitious roots. Insects are not the driving issue. The flare does not take up nitrogen. Mulch has little effect on pH within the root ball, and none of that would justify burying the trunk.

A five-gallon shrub comes out of the can with roots circling tightly around the outside of the root ball. What should the installer do?

• a.Plant it as is so the intact root ball is not disturbed
• b.Prune the top by a third to balance the restricted roots
• c.Score or tease the circling roots apart before backfilling✓
• d.Set it two inches deeper so the circling roots are covered

Circling roots continue to circle and eventually girdle the plant, so cutting or teasing them outward at planting is required. Planting as is preserves the defect. Pruning the top does not correct roots. Planting deeper buries the root crown, adds a second problem, and still leaves the circling roots in place.

What is the correct relationship between the root flare of a new tree and the surrounding finish grade?

• a.The flare is covered by four inches of amended backfill
• b.The flare is set level with the bottom of the watering basin
• c.The flare sits two inches below finish grade
• d.The flare sits at or slightly above finish grade✓

Planting with the flare at or slightly above grade keeps the trunk base dry and is the single most common difference between trees that establish and trees that decline. Setting the flare below grade or burying it under backfill traps moisture against the bark. A basin bottom sits below grade, so matching it would bury the flare as well.

Current practice for backfilling a tree pit in average native soil is which of the following?

• a.Backfill with imported topsoil to the full depth of the pit
• b.Backfill with native soil below and pure compost in the top foot
• c.Backfill with a fifty-fifty blend of native soil and nursery compost
• d.Backfill with the native soil that came out of the hole✓

Backfilling with native soil encourages roots to move out into the surrounding profile instead of staying in a rich pocket, and it avoids the texture interface that stalls water movement. Heavy compost blends, imported topsoil, and a compost cap all create that interface and can leave the tree rooted only inside the hole.

How wide should a planting hole be relative to the root ball, and why?

• a.Two to three times as wide, so loosened soil eases root spread✓
• b.Half again as wide, so amendment can be layered around the ball
• c.The same width, so the ball is held firmly on all sides
• d.Four times as wide, so a full drainage envelope can be created

A wide shallow hole gives new roots loosened soil to grow into laterally, which is where feeder roots actually go, and two to three times the ball width is the accepted range. A tight hole leaves compacted walls. Layering amendment around the ball creates a texture interface. Four times the width is unnecessary excavation with no added benefit.

A balled-and-burlapped tree arrives in a wire basket with synthetic burlap. What is the correct handling at planting?

• a.Leave the wrapping intact, since both materials break down in soil
• b.Set the tree, then cut away the upper basket and synthetic burlap✓
• c.Cut the burlap only at the top and leave the basket untouched
• d.Remove the basket entirely before the tree is set in the hole

Handling by the ball keeps it intact, so the tree is set first and the upper basket and all synthetic burlap are then cut away, since synthetic burlap never rots and wire can girdle roots. Leaving the wrapping intact assumes a decomposition that does not happen. Removing the basket before setting risks breaking the ball. Cutting burlap alone leaves the wire in place.

Two stakes are installed on a new tree. What describes correct staking?

• a.Ties pulled tight so the trunk cannot flex in any direction
• b.Ties placed just below the lowest branch and left for three seasons
• c.Stakes driven through the root ball for maximum holding power
• d.Ties placed low, allowing some trunk movement, removed within a year✓

Trunk movement builds taper and strength, so ties go low, stay loose, and come off once the tree anchors, usually inside a year. Tying high and leaving stakes for years produces a weak whippy trunk. Stakes driven through the ball damage roots. Rigid ties prevent the very movement that develops trunk strength.

In most of California, which season generally gives the best establishment for woody landscape plants?

• a.Late winter, when plants are fully dormant and shipping is easiest
• b.Midsummer, when nursery stock is fully hardened off
• c.Fall, when soil is still warm and winter rain follows✓
• d.Late spring, when soil has warmed and growth is rapid

Fall planting lets roots grow into warm soil while cool weather and coming rain reduce demand on the canopy, so plants enter their first summer established. Late spring gives only weeks before heat arrives. Midsummer planting stresses new roots hardest. Deep winter works for bare root stock but leaves cold soil and slow root activity for most container plants.

A shrub shows wilted foliage, and the soil around it is wet and smells sour. What is the most likely diagnosis?

• a.Transplant shock from root disturbance at installation
• b.Root rot from saturated soil starving roots of oxygen✓
• c.Drought stress that will resolve after one deep watering
• d.Salt burn from fertilizer applied at too high a rate

Roots need oxygen, and in saturated soil they suffocate and rot, which produces wilting that looks like drought while the soil is wet and smells anaerobic. Adding water makes it worse rather than better. Salt burn shows as marginal leaf scorch in dry soil. Transplant shock does not produce sour saturated soil.

A soil analysis reports a high electrical conductivity and a history of irrigation with hard well water. What management practice is indicated?

• a.Till the top foot to blend the salts through the profile
• b.Apply extra water periodically to leach salts downward✓
• c.Increase nitrogen so plants outgrow the salt injury
• d.Reduce irrigation volume so fewer salts arrive in the soil

Salts accumulate as water evaporates, and the only way to remove them is to move them downward with water applied beyond plant demand, provided the soil drains. Reducing irrigation concentrates salts further. Nitrogen fertilizer is itself a salt and adds to the load. Tilling redistributes salts without removing any of them.

Gypsum is recommended for a soil that has high sodium and poor structure. How does it work?

• a.It adds organic matter that binds soil particles together
• b.It increases the clay fraction so the soil holds more water
• c.It lowers soil pH directly by releasing free acid
• d.Calcium displaces sodium on clay particles so they can aggregate✓

Gypsum supplies calcium that exchanges with sodium on clay surfaces, letting particles flocculate into crumbs so water and air can move; the displaced sodium then leaches. It is neutral and does not lower pH the way sulfur does. It contains no organic matter and does not change the texture class of the soil.

A crew applies gypsum to a compacted clay pad that has normal sodium levels. What result should be expected?

• a.Slow improvement, because gypsum must first lower soil pH
• b.Rapid improvement, because gypsum increases infiltration on any soil
• c.Little improvement, because the problem is compaction not sodium✓
• d.Marked improvement, because gypsum loosens all clay soils

Gypsum corrects sodium-affected soils, and where sodium is not elevated it does very little, so the compacted pad still needs mechanical loosening and organic matter. It is not a general clay loosener, it does not raise infiltration on non-sodic soils, and it is not a pH-lowering material.

MWELO gives a compost incorporation rate for landscape areas where the soil report does not specify otherwise. Which statement reflects it?

• a.Six cubic yards per 1,000 square feet incorporated to a twelve-inch depth
• b.Two cubic yards per 1,000 square feet spread and left on the surface
• c.One cubic yard per 1,000 square feet worked into the top three inches
• d.Four cubic yards per 1,000 square feet incorporated to a six-inch depth✓

The ordinance default is four cubic yards of compost per 1,000 square feet of permeable area worked to a depth of six inches. One cubic yard at three inches is too little to change soil behavior. Compost left on the surface is mulch rather than incorporation. Six cubic yards to a foot exceeds what the ordinance requires and is rarely practical.CA MWELO (Title 23)

What is the primary long-term benefit of adding compost to a landscape soil?

• a.It builds structure, improving both water holding and aeration✓
• b.It supplies a high concentration of immediately available nitrogen
• c.It raises soil pH into the optimum range for most landscape plants
• d.It permanently changes the soil texture class toward loam

Compost feeds soil biology and builds aggregates, which improves water retention in sand and drainage in clay at the same time. Its nutrient release is slow and modest rather than concentrated. Texture is set by particle size and does not change with amendment. Effects on pH depend on the feedstock and are not a reliable benefit.

A designer is selecting turf for a full-sun sports lawn in the Central Valley that will go dormant in winter. Which choice fits?

• a.Creeping bentgrass, used on closely mown putting surfaces
• b.Perennial ryegrass, used mainly for quick cool-season cover
• c.Tall fescue, a cool-season grass that stays green in winter
• d.Hybrid bermudagrass, a warm-season grass that takes wear✓

Hybrid bermudagrass thrives in Central Valley heat, tolerates traffic, and naturally goes off-color in winter, which the owner has accepted. Tall fescue and perennial ryegrass are cool-season grasses that hold winter color rather than going dormant. Creeping bentgrass demands intensive management and is not a general sports surface.

A bermudagrass lawn is overseeded with perennial ryegrass in October. What is the purpose?

• a.To provide green cover while the bermudagrass is dormant✓
• b.To lower the water requirement of the lawn through winter
• c.To crowd out broadleaf weeds permanently from the stand
• d.To thicken the bermudagrass stand before it breaks dormancy

Overseeding puts a temporary cool-season grass over dormant warm-season turf so the lawn stays green until spring. It does not thicken the bermudagrass itself and in fact competes with it in spring. Water use goes up rather than down, and while dense cover suppresses weeds seasonally, the effect ends when the ryegrass fades.

A maintenance contract specifies the one-third rule for mowing. What does it require?

• a.Mowing height is lowered by one third going into summer
• b.No more than one third of the lawn is mowed in any single visit
• c.No more than one third of the leaf blade is removed at a cutting✓
• d.Clippings covering more than one third of the surface are removed

Removing more than a third of the blade at once strips the plant of the tissue that feeds root growth and causes scalping and thinning, so cutting height and frequency are set to stay within that limit. The rule is about blade removal, not the share of area mowed, not a seasonal height change, and not clipping cleanup.

A heavily used lawn drains poorly and the soil is hard underfoot. Which practice most directly relieves the condition?

• a.Top-dressing with a quarter inch of fine sand
• b.Core aeration that removes plugs and opens the profile✓
• c.Vertical mowing to cut through the accumulated thatch layer
• d.Raising the mowing height by half an inch

Core aeration pulls soil plugs out and leaves open channels for air, water, and roots, which is the direct remedy for compaction. Vertical mowing addresses thatch at the surface rather than compaction below it. Sand top-dressing smooths and amends slowly. A higher cut reduces stress but does not open compacted soil.

Sod is being laid on a prepared grade. Which installation practice is correct?

• a.Lay the sod on dry soil so the pieces do not slide out of line
• b.Stagger the joints in a running bond and butt the edges tightly✓
• c.Align all joints in straight rows so the seams disappear
• d.Leave a half inch between pieces so the roots can spread

Staggered, tightly butted joints keep the seams from drying out and knitting poorly, which is the usual cause of a checkerboard lawn. Gaps between pieces dry and fill with weeds. Continuous aligned joints create channels that erode and stay visible. Sod is laid on moist soil, since dry soil pulls water out of the new roots.

Why is new sod rolled lightly and watered immediately after installation?

• a.To press out air that would otherwise encourage disease
• b.To level the surface so the first mowing is uniform
• c.To ensure root contact with soil and prevent drying out✓
• d.To compact the soil below and reduce future settlement

Sod roots only where the mat touches moist soil, so light rolling closes air gaps and immediate water keeps thin roots from desiccating during the first days. Compacting the subsoil would work against rooting. Surface leveling is done during grading. Trapped air is a rooting problem rather than a disease mechanism.

A client wants a lawn established at the lowest material cost and can wait for coverage. Which method fits?

• a.Sprigging, which suits only certain warm-season grasses
• b.Seeding, which costs least but needs careful watering✓
• c.Sod, which gives an instant usable surface
• d.Hydroseeding, which is used mainly for large sloped areas

Seed has the lowest material cost and the client has accepted the wait, though it demands attentive irrigation while it germinates. Sod is the fastest and the most expensive. Sprigging is limited to grasses that spread vegetatively. Hydroseeding suits large or steep areas where broadcasting is impractical and costs more than plain seeding.

A crew is pruning a large limb from a mature tree. Where should the final cut be made?

• a.Leaving a six-inch stub that will drop off naturally
• b.Flush with the trunk so the wound closes smoothly
• c.At the midpoint of the limb to reduce weight first
• d.Just outside the branch collar so the tree can seal it✓

The branch collar contains the tissue that seals the wound, so the final cut goes just outside it. A flush cut removes that tissue and opens the trunk to decay. A long stub cannot be sealed and dies back. Reducing weight at the midpoint is a preliminary step in the three-cut method, not the final cut.

Why is the three-cut method used when removing a heavy limb?

• a.It prevents the falling limb from tearing bark down the trunk✓
• b.It allows the cut to be made without a chainsaw
• c.It reduces the diameter of the final cut by about half
• d.It leaves a stub that protects the wound through winter

An undercut and a relief cut let the weight drop away before the final cut, so the limb cannot peel a strip of bark off the trunk as it falls. The method has nothing to do with the type of saw. Any stub left by the second cut is removed by the third. The final cut diameter is set by the limb, not the method.

A client asks the crew to top a large shade tree to reduce its height. What is the professional response?

• a.Top it during dormancy when the tree can best tolerate the cuts
• b.Top it as requested but seal the cuts to prevent decay
• c.Decline topping and offer crown reduction to appropriate laterals✓
• d.Top no more than half the leaders and revisit the rest next year

Topping leaves stubs that decay and forces weakly attached sprouts, so accepted practice is to decline it and reduce the crown by cutting back to laterals large enough to assume the terminal role. Wound sealers do not prevent decay. Dormant timing does not make topping acceptable, and topping only half the leaders still produces the same defect.

What is the general limit on how much live crown should be removed from an established tree in a single season?

• a.Up to about half, if the tree is vigorous and well watered
• b.No more than about a quarter, to protect the food-producing canopy✓
• c.Up to about two thirds, if structural correction is needed
• d.No more than about ten percent, on any tree of any age

Leaves make the tree's food, so removing more than roughly a quarter of the live crown at once starves it and triggers stress sprouting. Half or two thirds is well past the point where decline begins even on vigorous trees. A ten percent ceiling is stricter than accepted practice and would make routine structural pruning impossible.

An aphid population appears on a hedge with lady beetles already present. Under integrated pest management, what is the reasonable first action?

• a.Apply a systemic soil drench as a preventive treatment
• b.Monitor and wash the aphids off, preserving the natural predators✓
• c.Apply a broad-spectrum insecticide to the entire hedge and surrounding beds
• d.Remove and dispose of every infested shoot on the hedge

Integrated pest management starts with the least disruptive effective action, and lady beetles already at work will often finish the job if they are not killed. A broad-spectrum spray removes the predators and invites a rebound. A preventive systemic drench treats a problem that may not develop. Stripping the shoots removes the plant along with the pest.

Sticky residue and black sooty coating appear on the leaves under a tree. What is the likely sequence?

• a.Hard irrigation water is leaving mineral residue on the foliage
• b.Sap-feeding insects excrete honeydew, and mold grows on the honeydew✓
• c.Air pollution is depositing particulates that stick to leaf surfaces
• d.A soil-borne fungus is moving up the trunk into the canopy

Aphids, scale, and whitefly excrete sugary honeydew, and sooty mold colonizes that film, so controlling the insect resolves both. A soil-borne fungus does not produce a sticky surface deposit. Mineral residue from hard water is white and chalky rather than black and sticky. Particulate deposition does not create a sticky sugar film.

Fine stippling and light webbing appear on shrubs beside a dusty driveway during a hot dry spell. Which pest is most likely?

• a.Spider mites, which increase in hot dry dusty conditions✓
• b.Thrips, which distort new growth as it expands
• c.Root weevils, which notch leaf margins at night
• d.Leafminers, which tunnel between the leaf surfaces

Spider mites build up in heat and dust and produce a stippled, faded leaf with fine webbing. Leafminers leave visible tunnels inside the leaf rather than surface stippling. Root weevils leave notched margins. Thrips cause silvering and distortion of expanding tissue, and neither weevils nor thrips spin webbing.

A pre-emergent herbicide is specified for a shrub bed. When must it be applied to work?

• a.At any point in the season, since it kills weeds on contact
• b.Before weed seeds germinate, then watered in to form a barrier✓
• c.Only after the bed has been cultivated to expose the seed bank
• d.After the weeds have emerged but before they set seed

A pre-emergent works on germinating seedlings, so it must be in place and activated by water before germination begins. Applying after emergence is too late because the product does not kill established weeds. It is not a contact material. Cultivating after application breaks the treated layer and undoes the barrier.

Bermudagrass is invading a shrub bed from the adjoining lawn. Which control approach is most durable?

• a.A pre-emergent applied twice a season along the edge of the bed
• b.A contact herbicide applied to the foliage on a warm day
• c.Hand pulling the visible runners each maintenance visit
• d.A physical edge barrier plus systemic control of the rhizomes✓

Bermudagrass spreads by rhizomes and stolons, so lasting control needs a barrier that stops lateral spread plus a systemic material that moves into the underground parts. Pre-emergents stop seed but not rhizome growth. Hand pulling breaks runners and leaves the rhizomes. A contact herbicide burns the top and the plant regrows.

A plant list is being reviewed for water efficiency on a Sacramento site. Which approach is most defensible?

• a.Select only plants native to the immediate watershed of the site
• b.Select species that stay under three feet so less canopy is watered
• c.Select species by regional water use ratings and group them by need✓
• d.Select evergreen species, since deciduous plants use more water

Published regional water use ratings let a designer choose plants that fit the climate zone and then group them into hydrozones that can actually be scheduled. Restricting to a single watershed is narrower than water efficiency requires. Mature size does not determine water use, and evergreen versus deciduous habit is not a reliable predictor either.

Groundcover is specified at 18 inches on center in a 200 square foot bed using triangular spacing. Compared with square spacing at the same interval, triangular spacing does what?

• a.Uses more plants and closes the bed more evenly✓
• b.Uses fewer plants but requires a wider border row
• c.Uses fewer plants and closes the bed more slowly
• d.Uses the same count but arranges plants in offset rows

Offsetting each row places plants closer to their diagonal neighbors, so a triangular layout fits more plants into the same area and fills in with fewer gaps. It does not reduce the count, and the count is not the same as square spacing at the same interval. Border treatment is a detail that does not change the underlying density.

What should determine the spacing between shrubs in a new foundation planting?

• a.The reach of the irrigation heads serving the bed
• b.The mature spread of the species being planted✓
• c.The width of the bed as drawn on the plan
• d.The size of the container the plants arrive in

Plants grow into their mature spread, so spacing set from that dimension avoids the crowded, sheared hedge that a tight installation becomes. Container size reflects nursery production rather than mature form. Bed width sets how many rows fit, not the interval. Irrigation layout should follow the planting design, not drive it.

A designer places a 40-foot shade tree eight feet from a two-story wall on the south side. What is the main problem?

• a.The mature canopy and roots will conflict with the structure✓
• b.The tree will need staking permanently because of wind eddies
• c.The tree will shade the wall and encourage mildew on the siding
• d.The wall will reflect heat and dry the root zone excessively

A tree with a wide mature canopy set eight feet from a wall will grow into the building and send structural roots under the footing area, which is a spacing failure that no maintenance can fix. Reflected heat, shading, and wind eddies are real site factors but are secondary to placing a large tree far too close to a structure.

During grading, fill soil is proposed to a depth of one foot over the root zone of a protected oak. What is the concern?

• a.Fill raises the pH of the root zone beyond what oaks tolerate
• b.Fill increases the weight the trunk must support during wind
• c.Fill reduces the amount of rainfall reaching the drip line
• d.Fill smothers roots by cutting off oxygen exchange at the surface✓

Tree roots respire, and a foot of fill blocks the gas exchange the surface roots depend on, which is why fill over root zones kills mature oaks slowly. Fill does not reliably change pH. Soil weight is carried by the ground, not the trunk. Rain still reaches the area, and moisture is not the mechanism of decline.

Where should the protective fencing be placed when a tree must be preserved through construction?

• a.At or beyond the drip line of the tree canopy✓
• b.Along the property line nearest the tree
• c.Three feet out from the trunk on every side of the tree
• d.At the edge of the proposed hardscape only

Most absorbing roots lie in the upper soil out to and past the canopy edge, so fencing at or beyond the drip line is what actually keeps equipment off them. A three-foot ring protects the trunk and almost none of the roots. Property lines and hardscape edges are unrelated to where the root system lies.

A bare-root rose arrives in January. What handling is correct before planting?

• a.Wrap the roots in plastic and hold it at room temperature
• b.Store it in full sun so the canes begin to break dormancy
• c.Keep the roots moist and shaded, and plant while still dormant✓
• d.Prune the roots back by half so they fit the planting hole

Bare-root stock has no soil to buffer it, so the roots must stay moist and cool and go in the ground while the plant is still dormant. Sun exposure breaks dormancy and dries the roots. Sealed plastic at room temperature encourages mold and heating. Cutting roots to fit removes the plant's stored resources; the hole is enlarged instead.

A hydroseed mix for a slope includes seed, fertilizer, wood fiber mulch, and a tackifier. What does the tackifier contribute?

• a.It dyes the slurry so the operator can see the coverage
• b.It supplies the nitrogen the seedlings use during germination
• c.It binds the slurry to the slope so it resists rain and wind✓
• d.It holds moisture at the seed until the first true leaves appear

A tackifier is a binder that glues the fiber and seed to the surface so a storm does not wash the application off. Nitrogen comes from the fertilizer in the mix. The green dye is a separate tracer component. Moisture retention is largely a function of the wood fiber mulch rather than the binder.

A landscape is being converted from lawn to a low water use planting. What preparation step most affects long-term success?

• a.Adding sand across the area to improve drainage before planting
• b.Applying a high-nitrogen fertilizer to the whole area at conversion
• c.Leaving the old sprinkler heads in place as backup irrigation
• d.Killing or removing the existing turf and its rhizomes completely✓

Surviving turf rhizomes will grow through a new planting for years, so full removal or kill is the step that determines whether the conversion holds. Sand over an existing soil creates a texture interface rather than drainage. High nitrogen pushes weed growth. Abandoned spray heads left in a drip conversion become leaks and confusion.

A soil report gives an infiltration rate of 0.15 inches per hour. What does that number govern in the design?

• a.The application rate the irrigation system may use without runoff✓
• b.The number of plants that can be supported per hundred square feet
• c.The total depth of water the root zone can store
• d.The depth to which compost should be incorporated

Infiltration rate is how fast soil accepts water, so it sets the ceiling on precipitation rate before runoff begins and drives the choice of low-rate nozzles or cycle-and-soak. Storage capacity is a different property tied to texture and depth. Plant density comes from mature size. Amendment depth is a specification, not a function of intake rate.

What does the term field capacity describe?

• a.The total pore volume of a soil sample when fully saturated
• b.The soil moisture level at which plants can no longer extract water
• c.The moisture a soil holds after free drainage has stopped✓
• d.The moisture content at which a soil can be safely compacted

Field capacity is the water remaining after gravity has drained the large pores, and it is the upper end of the plant-available range. The point where plants can no longer extract water is the permanent wilting point. Total pore volume at saturation is a different measure. Optimum moisture for compaction is a construction property, not a plant-water term.

Why does deep, infrequent irrigation generally produce healthier established plants than daily light watering?

• a.It lowers salt concentration in the upper few inches of soil
• b.It wets the full root zone and encourages roots to grow deeper✓
• c.It reduces the total volume of water the landscape consumes
• d.It keeps soil temperature more stable through the growing season

Water only reaches the depth it is applied to, so deep cycles draw roots downward into a larger reservoir while daily sprinkles keep roots shallow and dependent. Total volume depends on the schedule, not the pattern. Soil temperature is affected mainly by mulch and season. Deep watering can move salts down but that is a side effect rather than the main mechanism.

A newly planted landscape is on the same schedule as the mature planting next door and the new plants are struggling. What is the likely reason?

• a.New plants require more fertilizer than the mature planting receives
• b.New root balls dry faster and need their own establishment schedule✓
• c.New plants need a lower mowing and pruning frequency than mature ones
• d.New plants are more sensitive to the mineral content of the water

A fresh root ball holds a small volume of nursery mix that dries far faster than surrounding soil, so new plantings need a separate, more frequent establishment schedule until roots move outward. Fertilizer, water mineral content, and maintenance frequency all matter less than the mismatch between a small root ball and a mature-planting schedule.

A shrub was planted three inches too deep two years ago and is now declining. What is the appropriate correction?

• a.Cut the top back by half to balance the buried root system
• b.Increase fertilizer and irrigation to push new growth
• c.Install a drainage sump beside the plant to draw water away
• d.Excavate the excess soil back to expose the root crown✓

A buried crown stays wet and rots, so removing the excess soil to expose the crown is the direct fix. More fertilizer and water push growth onto a failing root system. Cutting the top back removes food production without addressing the burial. A sump drains soil water but does not uncover the crown that is decaying.

An arborist reports Armillaria root disease in a bed where oaks are declining. What management step is most relevant to the C-27 contractor?

• a.Apply a broad-spectrum fungicide drench across the entire bed
• b.Reduce summer irrigation near the trunks and improve drainage✓
• c.Replant the same species and treat the backfill before installation
• d.Increase irrigation frequency to reduce stress on the remaining trees

Armillaria advances in wet soil around the root crown, so cutting summer water near trunks and improving drainage is the practical control available on site. Soil fungicide drenches do not reliably reach the fungus. Adding water encourages it. Replanting susceptible species into infested soil repeats the failure.

Which condition best describes when a bed is ready for finish raking and planting?

• a.The soil has been rolled to remove all surface texture
• b.The soil is moist but crumbles rather than smearing when squeezed✓
• c.The soil is wet enough that it ribbons between the fingers
• d.The soil is dry enough that it powders under the rake

Soil worked at the crumbly moist stage keeps its structure, while soil worked wet smears into clods and soil worked bone dry turns to dust and blows away. A soil that ribbons is too wet to work. Rolling out all surface texture seals the soil and reduces the infiltration a new planting depends on.

A specification calls for six inches of imported topsoil over a native clay subgrade. What must be done at the interface?

• a.Place two inches of gravel between the layers to promote drainage
• b.Place a filter fabric between the layers to keep them separate
• c.Scarify the subgrade and blend the two soils at the boundary✓
• d.Compact the subgrade to a smooth sealed surface before placing topsoil

A sharp change in texture stalls water movement, so scarifying and blending at the boundary lets water and roots cross it. A sealed compacted subgrade guarantees a perched water table. Fabric between soil layers is a root and water barrier. A gravel layer between two soils makes the perching worse rather than better.

Turf is specified under the canopy of dense mature trees on the north side of a building. What should the contractor raise with the designer?

• a.That the turf will require a separate backflow assembly
• b.That the trees should be staked before the turf is installed
• c.That the trees will need to be fertilized more heavily
• d.That the shade and root competition make turf a poor fit✓

Deep shade plus tree root competition for water and nutrients keeps most turf thin no matter how it is managed, so a shade-tolerant groundcover or mulch is the better recommendation. Fertilizing the trees does not create light. A backflow assembly serves the whole system rather than one area. Mature trees do not need staking.

A landscape uses ammonium sulfate as its nitrogen source year after year. What effect should be anticipated on soil chemistry?

• a.Soil organic matter increases steadily over time
• b.Soil pH drifts upward toward the alkaline range
• c.Soil pH drifts downward as the material acidifies the soil✓
• d.Soil salinity falls because sulfate leaches other salts

Ammonium sulfate is an acidifying nitrogen source, so repeated use pushes pH down, which can be useful on alkaline soil and harmful where pH is already low. It does not raise pH. It contributes no organic matter. It is a salt itself, so it adds to salinity rather than reducing it.

Older leaves on a hedge are uniformly pale while new growth stays green. Which nutrient is most likely short?

• a.Calcium, which moves only in the transpiration stream
• b.Zinc, which is required in very small amounts
• c.Iron, which is immobile within the plant
• d.Nitrogen, which the plant moves from old leaves to new✓

Nitrogen is mobile, so a deficient plant pulls it out of old leaves to supply new growth, which yellows the oldest foliage first and uniformly. Iron and calcium are immobile and show their symptoms on new growth instead. Zinc shortage produces small distorted new leaves rather than uniform pale older foliage.

A homeowner reports the new lawn is yellowing and says it is watered for 30 minutes every evening. What should the contractor check first?

• a.Whether the mowing height has been lowered too far
• b.Whether the seed variety matches the exposure of the site
• c.Whether the fertilizer applied at installation has been exhausted
• d.Whether the soil is staying saturated and starving roots of air✓

Nightly watering on most soils keeps the profile saturated, and roots without oxygen yellow in a way that looks exactly like a nutrient shortage, so the schedule is the first thing to test with a probe. Mowing height, variety selection, and fertilizer timing are all worth reviewing, but none explains yellowing under a clearly excessive watering pattern.

What is the practical purpose of a soil probe or auger in routine landscape maintenance?

• a.To collect samples for the required soil management report
• b.To measure the pH of the root zone in the field
• c.To determine the compaction percentage of the subgrade
• d.To check how deep applied water actually penetrated✓

Pulling a core after a cycle shows whether water reached the root zone or stopped a few inches down, which is the fastest way to correct a schedule. Field pH requires a test kit or meter. Compaction percentage requires a density test, not a hand probe. Samples for a formal report are collected to a laboratory protocol rather than casually.