University of Maryland Extension

Prepare Your Soil

How to Prepare Soil for a Vegetable Garden

Soil supplies plants with water, nutrients, and mechanical support. It may be tempting to postpone some of the following steps but it will be much harder to correct poor soil problems with plants already growing in the ground.

  • Ideal vegetable garden soil should be loose, deep and crumbly. It should drain well (water should not stand on top after rain) and contain plenty of organic matter (see below). Good garden soil will deliver the right mixture of air, water, and nutrients to grow a large root system and strong, productive plants.
  • Have your soil tested to determine nutrient levels and pH, and to be sure it is safe to plant in (low lead level). The pH level should be in the 6.2-6.8 range.

So how do you turn a small area of lawn into a veggie garden? A small plot (less than 100 sq. ft.) can be prepared using hand tools. Here are three options that work well.

Option 1: Cover it 

You can kill the grass by covering it with sections of newspaper and then covering that with a layer of shredded leaves and grass clippings (no herbicides) and top it off with a layer of compost. This is best done in the fall but the method can also work in early spring- it may take 4-8 weeks for the sod to die. You can then turn the soil, see “Dig it” below, or plant seeds and transplants directly into the compost. This approach is sometimes referred to as sheet composting.

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Cover new garden area with cardboard or newspaper sections

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Dump compost on the newspaper or cardboard

compost leaves grass clippings
Compost, leaves, and grass clippings, and shredded leaf mixture

Several gardening authors (e.g., Pat Lanza, "Lasagna Gardening"; and Lee Reich, "Weedless Gardening") have popularized this method of no-till soil preparation and gardening.

Whichever method you choose, you should always strive to:

  1. Improve your garden soil with organic matter.
  2. Keep your garden soil covered as much as possible throughout the year to prevent soil erosion and nutrient run-off, and keep weed seeds from germinating.

Option 2: Slice it

Push a garden spade (flat, rectangular blade) through the top 2 inches of sod and soil, parallel with the ground. Some people can do this best on one knee. Sod contains valuable topsoil and organic matter and should not be thrown out. Instead, turn it over to dry and kill the roots. After the sod turns completely brown it should be mixed back into the soil.

tools spade garden fork
Garden spade and garden fork

turf removal
Slicing the sod using a garden spade

While you wait for the sod to die, spread a 2-4 inch layer of compost over the garden site. Then spread the dead sod and topsoil you removed and mix it all together.

Option 3: Dig it

Cut through the sod 8 inches down into your soil with a shovel or mattock. Lift the soil with sod attached and turn it on its side. Repeat until all of the soil is turned. Cut the sod into small pieces to accelerate decomposition or turn the large sod pieces so that the roots are facing up. You can use a garden fork to loosen compacted subsoil. Insert the fork and rock it gently back and forth to the subsoil.

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Turning topsoil over with a garden spade

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Loosening subsoil with a garden fork

It will take 4-8 weeks in the spring for the sod to fully decompose. You can remove small sod pieces with a metal rake prior to planting and let them finish decomposing next to your garden or in your compost pile.

Adding organic matter

What is organic matter?

Plants and animals that are alive, dead, or in some stage of decomposition. The stuff we think of as dead (e.g. brown, dried up leaves) is teeming with microbial life. There may be a billion living microorganisms in a teaspoon or compost or soil!

Why is it important?

Organic matter is the key to improving soil quality which, in turn, leads to healthy, productive plants. It improves the structure of soils that are high in clay or sand so that roots can better grow and take advantage of available water, air, and nutrients.

The concept “feed the soil and the soil will feed your plants” is very important for vegetable gardeners. If you feed your soil different types of organic matter on a regular basis you provide food for soil-dwelling organisms. The vast majority of these- bacteria and fungi- cannot be seen without a microscope. They breakdown organic materials, consume each other, and cause the release of nutrients that roots can pick up.

Your soil is improved with every addition of organic matter. You are building up a reservoir of slowly released nutrients that increase your garden’s productivity over time. You will need to use fertilizers to make sure that your plants have the nutrients they most need (e.g. nitrogen) when they need it. But your reliance on organic or synthetic fertilizers will probably decrease as your organic matter content increases.

What should I use and where do I get it?

Compost- you can make your own from leaves, grass clippings, kitchen scraps, farm manure (no pet waste),  and other materials. Every vegetable gardener should have a way of recycling organic wastes into compost. For more information read (PDF) HG 35 Backyard Composting. Contact your county/city government to see if compost is available at your local landfill.

You can also purchase compost by the bag or cubic yard (pick-up truck load). Some examples are LeafGro® and other composted yard waste products,and mushroom compost from PA. Home-made or purchased compost can be added any time of year and can be used as a top-dressing or mulch during the growing season.

Leaves and grass clippings- from your own yard or neighborhood. Shredded leaves are best because they rot faster than whole leaves. Spread them out on top of your garden in the fall and turn them under in the spring.  Grass clippings (no herbicides) can be used as a mulch around vegetable plants or add them to your compost pile.

Manure- animal manures (sheep, cow, horse, chicken) may be available free of charge in your community. They are very good for improving soil quality and add valuable nutrients to the soil.

There are some risks to consider. Fresh manure can burn plant roots, and un-composted animal manures may contain human pathogens. Manures are considered fully composted when the pile or windrow reaches at least 130ºF for 3 consecutive days. This kills most plant and human diseases, and weed seeds. Most farmers with animals do not actively compost and monitor their manure to this standard. So, it’s best to treat any animal manure you can locate as un-composted. Here’s the U.S.D.A.’s  National Organic Program standard for using un-composted animal manure: apply no less than 90 days prior to harvest if there’s no contact between crop and soil, (e.g., staked tomatoes) or 120 days prior to harvest if the crop is in contact with soil, (e.g., cabbage). Do not apply un-composted manure after crops are established. Fall application and incorporation is recommended for home gardeners.

  • Composted animal manures have a somewhat higher nutrient content than plant-based compost
  • Light incorporation of manure is desirable to prevent nutrients from washing away
    Never use dog or cat manures in your vegetable garden
  • Horse manure may contain many weed seeds; be prepared to control weed growth early on
  • Make compost teas from plant-based composts
  • Wash all produce thoroughly after harvest

Other sources- kitchen scraps buried in holes or trenches in your garden soil; plant roots- cut the tops of plants that have finished producing and leave the roots in place to rot; cover crops, decomposed mulches.

How much should I add?

Fresh organic materials lose more than half their volume by the time they are fully decomposed. The best option, if available, is to add compost to the soil. After a few years of large additions, you can decrease the amount to 1 in. each year. It takes 8 cubic feet of compost to cover a 100 sq. ft. garden to a depth of one inch. The goal is to have organic matter comprise 25 to 30% of the top 8 inches of soil by volume.

soil conditioner
Home-made compost in bushel basket, leaves
in wheelbarrow, commercial bag of LeafGro,
bag on right is shredded leaves and grass
clippings picked up with a mulching mower.

See also: Soil for Containers 

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