how deep soil for vegetable garden

how deep soil for vegetable garden

By: Priscilla Recordsdata, Michael Arnold, Douglas Welsh, and Frank Dainello

Planning a Raised Mattress Backyard

figure-728-a-raised-bed-gardenRaised beds are freestanding backyard beds constructed above the pure terrain. Texas gardeners are discovering that raised mattress gardens will help clear up many issues. In lots of areas of the state the soil incorporates an excessive amount of sand or clay, or is just too alkaline for some vegetation to develop effectively. Soil that’s poorly aerated due to compaction or poor drainage additionally could also be an issue. Soil high quality issues are sometimes aggravated in city and suburban settings, the place topsoil and vegetation have been eliminated or the grade modified throughout building.

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Raised mattress gardens enhance rising circumstances for vegetation by lifting their roots above poor soil. Soil within the beds may be amended to offer a greater rising medium for vegetation, even vegetation that may not naturally thrive there. The soil in raised beds warms up earlier within the spring and is much less apt to be invaded by sure grasses and by tree roots. Additionally, the peak of raised beds could make them simpler to keep up.

Web site Choice

Step one in planning a raised mattress is deciding the place it is going to be situated. Web site choice and plant choice go hand in hand. Many greens, ornamentals and herbs require a variety of daylight; a mattress for these vegetation must be situated the place it can obtain full solar. If that’s not attainable, choose a website that receives morning fairly than afternoon solar. If solely shady websites can be found, attempt rising cool season greens that tolerate shade, akin to broccoli, cabbage and lettuce. Additionally, some decorative vegetation do greatest in partial shade. In windy areas, place beds the place they’re shielded from prevailing winds by fences, buildings or different buildings. Beds shouldn’t be situated in frost pockets or the place air circulation is poor as a result of fungal illnesses typically develop the place there’s little air circulate.


A raised mattress ought to drain effectively as a result of soil that is still very moist will deprive plant roots of oxygen. Additionally, plant illnesses develop extra simply beneath moist circumstances. Good drainage is very necessary in vegetable beds. The soil and the situation decide how effectively a raised mattress will drain. If the mattress incorporates clay soil, it must be amended with at the least one third by quantity of coarse sand, natural matter or a rough grade of perlite to enhance drainage.

Don’t find a mattress in a marshy space the place it can sit in water. Assemble panorama beds in order that they slope about 2 p.c (a ¼ inch drop per foot of horizontal distance) away from any buildings, or away from the middle of the mattress. Generally it’s crucial to put in particular drains; decide this in the course of the strategy planning stage. Drain tiles or septic line tubing may be prolonged the size of the mattress and thru the partitions at both finish to create a drainage channel. Usually, one line each 4 to six ft is enough. One other manner is to dig a trench within the desired course of water circulate (from the mattress to a decrease elevation), lay 3 to 4 inches of coarse stone within the trench, after which lay tiles or perforated tubing fabricated from clay, concrete or plastic within the heart of the ditch. Cowl the ditch with extra coarse stone after which soil. The French drain, one other various, is just a slim trench full of coarse stone main from a poorly drained space to a decrease elevation.


A raised mattress ought to mix with its environment. The mattress’s design could also be formal or casual, relying on its form and the type of edging chosen. An oblong mattress edged with a low brick wall, and full of yaupon (Ilex vomitoria) or boxwood (Buxus spp) pruned into straight hedges or topiaries, has a proper look that may be acceptable within the entrance of a home. An irregularly formed perennial border tucked behind a dry stone wall is much less formal, however may very well be enticing nearly anyplace within the panorama. A vegetable backyard has an off-the-cuff look that works greatest in non-public areas of the yard. The dimensions of the mattress must be saved in proportion to the house round it.

A raised mattress doesn’t should be very deep to be efficient. Eight to 12 inches is normally enough. If drainage is an issue, or if the vegetation you’re rising want drier soil, the mattress may very well be taller and full of a porous rising medium. Vegetable beds must be 12 to 18 inches deep. The fabric used to edge a raised mattress must be secure, sturdy and enticing. It’s the edging that provides the mattress its “look” inside the panorama. It additionally establishes the define of the mattress and holds the soil in place. Edging could also be so simple as metallic strips, railroad ties or panorama timbers, or as intricate as a mortared brick or stone. A crested mattress is one during which the soil is just mounded from the perimeters of the mattress to the middle; it could or could not have an edging.

Metallic edging is available in 8- to 10-foot lengths, is simple to put in, and is handy for edging curved beds. Nonetheless, it might probably rust with time, and until plantings overflow the mattress or the edging is camouflaged with a extra aesthetic materials, it might not be as enticing as you desire to. Ties and timbers may be laid singly or in layers and have a country look. Railroad ties handled with creosote don’t seem to pose any well being issues as a result of many of the creosote has leached away. There may be some controversy about utilizing handled panorama timbers, however research have proven that any compounds that leach out are effectively inside protected ranges established by the EPA, each in rising media and in harvested produce. In case you are involved about utilizing handled timbers, line the within of the mattress partitions with polyethylene, roofing felt or related supplies to type a protecting barrier. Stone partitions make fascinating beds, and may be constructed with cracks and openings for artistic plantings.


Nonetheless, stone may be costly. Interlocking pavers are more and more fashionable and are simpler to put in than mortared stone. Whichever edging materials you select, it must be sturdy sufficient to carry the rising media and face up to being ran into or ridden over by a driving garden mower. It must be put in correctly and complement the remainder of the panorama.


The design part is one of the best time to determine how you’ll irrigate your raised mattress. Hand watering could also be easiest in lots of instances, however it might probably change into tedious; the gardener should additionally know when and the way a lot to water or vegetation will undergo.

With an automatic sprinkler system beds may be watered frequently with little effort, however this technique will moist the foliage, which contributes to illness and salt harm. If the system is robotically timed it could come on whether or not or not there was latest rainfall, and thus waste water. So, an automatic system often is the most handy for the gardener, however it isn’t essentially greatest for the vegetation. Pop-up or stationary risers are susceptible to evaporation and drift throughout windy circumstances. Low-flow methods may be extra environment friendly beneath heat, windy circumstances.

Low-flow irrigation methods that work effectively for woody vegetation and greens embody microsprinkler, drip, trickle and soaker hose methods. These methods preserve water, may be put in beneath mulch, may be regulated to circulate at charges particular person vegetation want, and are much less prone to moist foliage. Nonetheless, they do have some disadvantages. Emitters are susceptible to clogging until the water used may be very clear, and if emitters are put in beneath mulch it’s troublesome to identify issues. Emitters are additionally delicate to elevation adjustments alongside the irrigation line and require strain compensating traces. Lastly, rodents and different wildlife can simply harm some drip traces.

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Should you select a sprinkler system, determine what number of sprinkler heads you will have and whether or not sprinkler heads will pop up or be set on risers. Be sure you take into account the spray overlap, angle of spray and top of the sprinkler heads. All the time design the system in order that at the least one further riser per part may be added later. Chances are you’ll want this flexibility as your plantings mature. Should you select drip or trickle irrigation, decide the size of the hose and the variety of emitters you will have. Drip tape with 12-inch emitter spacing is greatest for greens.

Beds must be divided into watering zones in response to the vegetation wants, the scale of the system, the obtainable water strain, and the quantity of water circulate obtainable. Zone watering may be guide or timed. No single irrigation system is acceptable for all raised beds. Generally a mix of methods works greatest.


Developing a Raised Mattress Backyard

Lay out the Perimeter

If the mattress has straight traces, use stakes and string to stipulate the perimeter. Backyard hose or rope works effectively for outlining curved beds. Most vegetable beds are sq. or rectangular in order that greens may be planted in rows. Many decorative beds are curved. To make upkeep simpler, notably mowing, design the mattress with lengthy, flowing curves fairly than many tight ones.


Take away Current Vegetation

Take away any woody vegetation with loppers, hand saws or chainsaws, after which dig out the roots. Apply a systemic herbicide to kill perennial weeds and forestall them from returning. Or, kill vegetation with out herbicide by masking the mattress space with clear plastic (anchor edges with rocks or soil) for 1 to 2 months. If each day and evening temperatures are heat, the warmth generated beneath the plastic will kill vegetation, although not as rapidly as herbicides. As soon as the location is evident of vegetation, you need to until the soil completely.

Set up Edging

Metallic. Metallic edging is normally a 4- to 6-inch broad metallic strip in various lengths. They’re linked by stakes which might be inserted by means of overlapping notches. Place the strips on edge alongside the perimeter of the mattress and overlap the ends, lining up the notches. Hammer the stakes into the soil by means of the overlapping notches. Utilizing a rubber mallet or a bit of wooden between a hammer and the highest of the edging, flippantly hammer the edging into the soil between the stakes. It’s best to partially sink the stakes till all are in place, after which sink them to the specified depth. If the soil is tough and dry, use water to melt it, or excavate the soil to accommodate the edging.

Brick/Cinder Blocks. To construct a brick-edged raised mattress, first pour a concrete footer at the least 6 to 12 inches excessive and 16 to 18 inches broad. This would be the base of the wall. Dig the ditch for the footer fastidiously in order that you’ll not want to make use of varieties. As soon as the concrete is poured, work a 3 ⁄8-inch reinforcing rod into the middle for stability (particularly necessary in clay soils). Clean the highest of the footer with a trowel. After the footer has cured for 3 or 4 days, moist it and apply about 3 ⁄4 to 1 inch of mortar about 2 ft down the slab. Press the primary brick into the mortar in order that about 1 ⁄2 inch of mortar is left between the brick and slab. Apply mortar to the facet of the subsequent brick and place it 3 ⁄8 inch from the primary one. Rap the brick gently with the trowel deal with to set it and take away the surplus mortar squeezed from between the bricks. Proceed till the edging is full. Cinder block edging could not require mortar as a result of the blocks are bigger.

Stone. To lift the stones, roll them up a plank on pipes or use a hydraulic carry. To put in a dry stone wall, first stage the terrain of the perimeter. Lay the stones in every row in order that they overlap the stones beneath. Make the wall wider on the base than on the high, and may’t the stones inward for stability. If the wall is to be multiple stone thick, periodically insert tie stones/lengthy stones laid throughout the width of the wall. This makes the wall stronger. If the wall is to be greater than 2 ft excessive it must be mortared in place and constructed on a concrete footer. Take a look at match two or three stones at a time earlier than making use of mortar. To make sure good contact between the mortar and stones, lay the primary layer of stones whereas the footer remains to be moist and rap the stones sharply with the trowel deal with to set them. If the stones are heavy, insert wood pegs between the stones to maintain the mortar from being squeezed out earlier than it dries. Take away the wood pegs after the mortar has partially set and fill the holes with mortar. You might have considered trying professional assist as a result of an improperly constructed stone wall may be hazardous. Additionally examine native ordinances to find out whether or not an architect’s seal is required for the plans.


Panorama Timbers. Stage the perimeter of the mattress in order that the primary layer of timbers is stage or set on the desired slope. Drive rebar or galvanized spikes roughly 12 to 18 inches into the soil by means of the ends of the timbers at 20-degree angles to the middle of the timber. Overlap successive layers of timbers and nail them to the earlier layer with galvanized spikes. Verify the extent or desired slope ceaselessly throughout building.


Set up Irrigation System

If you’ll have drainage trenches or an computerized sprinkler system, set up them earlier than soil is added to the mattress.

Add Soil

To assist preserve garden grasses out of the mattress, particularly bermudagrass (Cydonon dactylon), it is best to set up a weed barrier between the edging and the soil. Then you’re prepared so as to add soil or rising media.

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The soil ought to maintain water effectively sufficient in order that plant roots don’t dry out, however it also needs to have good drainage. Soil with an excessive amount of sand doesn’t maintain water effectively; soil with an excessive amount of clay doesn’t drain effectively. Typically, a sandy clay loam soil is greatest for many vegetation. It must be combined with natural matter akin to peat moss, composted manure, sawdust or floor bark. Cacti and succulent beds could require extremely aerated supplies like crushed granite that maintain little water.

Soil is bought and delivered by the cubic yard and may be ordered as a topsoil/compost mix. Frequent mixtures are three-fourths topsoil and one-fourth compost, twothirds topsoil and one-third compost, or half topsoil and half compost. The upper the natural materials content material the earlier you will have so as to add extra soil/compost to the mattress, as a result of the natural matter breaks down over time. Make sure that natural materials has been composted earlier than it’s added to the soil. In any other case, it can deprive vegetation of nitrogen because it decomposes. The perfect media for greens consists of one-third topsoil, one-third peat moss and one-third sand or coarse perlite. Normal potting soil or business container mixes are additionally good for rising greens, however are normally too costly for filling massive beds. When filling the mattress, grade the soil in order that it slopes barely away from the middle of the mattress to the sting, and away from adjoining buildings.

It may be troublesome to include present timber or shrubs right into a raised mattress. The simplest technique is to encircle the plant with metallic edging to maintain soil and extra mulch away from the crown of the plant. Go away as broad an area as attainable between the edging and the plant. Tree wells can be utilized in taller beds. You will need to bear in mind, although, that including massive portions of soil over the roots of established vegetation could kill them.

Planting and Mulching a Raised Mattress Backyard


Be certain the vegetation you choose are tailored to the local weather and water in your space, and that their mature measurement shall be acceptable for his or her location within the panorama. Perennials and everlasting timber and shrubs must be situated on the rear of the mattress the place they are going to be least disturbed. Plant annuals alongside the sting the place they are going to be simple to achieve when it’s time to substitute them.


Mulching could also be crucial of entirety to your raised mattress backyard. Mulch retains plant roots cool in summer season, reduces water evaporation from the soil, controls erosion by softening the influence of rain and slowing runoff so it might probably soak into the soil, and suppresses weeds. Mulches additionally add to the attractiveness of the panorama.

After all of the vegetation are within the mattress, apply a 2- to 3-inch-deep layer of mulch, tapering it to the bases of the vegetation. To find out how a lot mulch you want, multiply the size of the mattress by the width and by the depth of mulch you need. Divide this whole by 12 after which once more by 27 to acquire the quantity of mulch in cubic yards.

Bark and pine needles are each fashionable mulches. Many vegetable gardeners use shredded newspaper or strips of black plastic anchored down the rows. Seeds or seedlings are planted in holes minimize within the plastic. Newspaper and uncovered plastic should not notably enticing and will in all probability be reserved for personal areas of the backyard.


Sustaining a Raised Mattress Backyard


Sustaining a raised mattress backyard entails weeding, irrigating, pruning, and changing decomposed mulch, and eradicating spent vegetation. Listed here are some tips for maintaining your backyard wanting its greatest.

  1. Irrigate the mattress when wanted, letting the highest inch of soil dry out between watering. If the plant species are complementary, their water necessities shall be related.
  2. Preserve 2 to three inches of mulch on the mattress. The mulch must be acceptable to the area, maybe pine straw or wooden chips in East Texas and stone or gravel in West Texas.
  3. Add compost or top-dress with natural mulches twice every year within the spring and fall. This replenishes the soil and acts as a sluggish launch fertilizer. Merely rake again the mulch, add the compost, and substitute the mulch or add new mulch over the previous. Or, add an inorganic sluggish launch fertilizer earlier than and through energetic plant development.
  4. Prune every plant correctly in response to its use and the supposed design.
  5. Management insect pests and illnesses. You possibly can scale back the necessity for chemical therapies by training built-in pest administration: begin with good high quality vegetation; deal with vegetation fastidiously earlier than and through planting; choose vegetation which might be tailored to your area.

A correctly designed, constructed and maintained raised mattress shall be an enduring supply of magnificence in your panorama.

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