How to Prepare Soil for Planting Vegetables

The ideal soil for growing vegetables is loam, a mix of clay, sand and silt with active organisms, nutrients, water permeability, and a balanced pH, but garden soils rarely start out as loam. Even though vegetables are tolerant of variable soils and will produce in adequate conditions, there are several steps you should take to correct deficiencies before you turn over your soil.

Evaluate Your Soil

Your first step before sowing seed or transplanting vegetables is to learn if your soil is sufficient to feed your crop. Making a few adjustments before you plant can save time and effort and improve your chances of a good harvest..

Perform a Soil Test

A soil test measures the pH which determines the levels of acid and alkalinity in the soil. Maintaining the correct pH level is important because it affects the ability of vegetable crops to take up nutrients. Most vegetables grow best in a balanced pH between 6.2 and 6,8.

The most accurate method for measuring the pH level is to take a mixed soil sample to your cooperative extension office. Your agent can tell if the sample is too acidic or alkaline and offer suggestions for corrections. DIY soil test kits are available commercially or you can perform your own test with simple kitchen ingredients.

To take a good sample, dig down 8 to 10 inches with a shovel and remove a handful of soil for testing. If you plan to grow a large garden, take samples from several locations.

Check Moisture Level

Check the texture of your soil. It should be moist and crumbly but not wet. Working wet soil causes compaction which can damage the structure and adversely affect roots. Since roots enable photosynthesis which feeds your crops, they require air and water. Below the surface this is referred to as water or soil permeability.

With just your eyes, fingers and a shovel, you can evaluate the texture of your soil. Dig down 8 to 10 inches with a shovel and remove a handful of soil. If you can mold it into a ball or worm, it is too wet to turn over. If it crumbles instead of holding a molded shape, it is dry enough to till or dig. If it retains water and stays wet, it will appear gray and mottled just below the surface. Brown or reddish subsoil indicates the soil is well-draining

Amend the Soil

Experienced gardeners sometimes say they are growing soil as well as crops. The best way to improve soil for the long term is to add organic material annually. Commercial fertilizers can offer a seasonal fix and provide nutrients almost immediately, however they are quickly used up and need to be applied repeatedly.

Adjust the pH

Raising or lowering the pH level is an easy process achieved by adding lime or sulphur. An application of lime raises pH making it more alkaline. Sulphur lowers pH for more acidic soil. If your DIY soil test indicates a poor pH level, start by adding either lime or sulphur in small amounts and retest until the desired level is reached.

Add Compost and Organic Material

Adding a 2 to 3 inch layer of compost or organic material annually keeps your soil healthy in a number of ways. Dry leaves, grass clippings and compost can be applied in the fall or early spring and tilled or dug in. Another alternative is to plant a spring or fall cover crop like clover. As these materials break down they add nutrients, raise nitrogen levels and attract the organisms and microorganisms that improve soil texture. Since the material must first be broken down, adding organic material is a slow, ongoing process with long lasting results.

Apply Commercial Fertilizer

If you are just starting a garden or don't have available time or material for adding compost, commercial fertilizers can quickly provide the nutrients your plants need. Ammonium nitrate added, according to the manufacturers label, will boost nitrogen and should be applied just before planting; it can burn the leaves of existing plants. It may be a listed ingredient in liquid fertilizers or be purchased in granular form. Granular fertilizers should be dug, tilled or watered in.

Depending on your soil test results, you may need to add other primary nutrients. Reading labels will help you understand what percentage of each primary nutrient makes up the mix as well as any secondary nutrients, resins and fillers.

Commercial organic fertilizers like bloodmeal and fish emulsion work well for small individual crops and are usually added during or after planting. They are not cost efficient for pre-treating a large garden.

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Work the Soil

No matter the composition of your soil or any amendments you've added, it has to be worked up to make it ready for planting. The goal is to create a loamy surface over a well-draining subsoil. This means you need to dig or til to turn over about a foot of topsoil.

Manual digging can be physically taxing but works well for small gardens. This is a multi-step process that starts with a shovel; digging down about a foot and turning over the soil. The next step is to break up large clumps and clods with a hoe or garden fork. Finally, the garden area should be raked smooth. Preparing the garden site manually causes less damage to soil structure and any beneficial organisms present.

Using a tractor tiller attachment or walk-behind tiller saves labor in a large garden. Several passes may be required but this is still a one-step process that reduces the soil to a crumbly, workable texture ready for planting.