Now is a good time to test your garden soil

By Connie Mehmel
WSU Chelan/Douglas County Master Gardener
March 24, 2022

image of shovel in the soil.
For a soil test, collect from the rooting area, about 6 to 8 inches deep, says WSU Master Gardener Connie Mehmel.
Provided photo/Connie Mehmel

Connie Mehmel
Connie Mehmel – WSU Chelan/Douglas County Master Gardener – Provided photo

As you ready your garden beds for flowers and vegetables, it’s important to know some things about your soil. Soil supports and nourishes your plants, so you want to know if it has the nutrients your plants will need to get off to a good start.

Soil is dynamic. Nutrients are continually added by the weathering of rocks, minerals and organic matter, and the actions of living organisms such as bacteria, fungi and microbes. Nutrients are continually removed by leaching and the action of microbes that convert plant-available nitrate to nitrogen gas. You also remove nutrients by harvesting your vegetables and flowers.

Before you start spring planting, you might want to check your soil fertility with a soil test.

If you have had your garden soil tested in the last three years, you probably don’t need another one. You should seriously consider a soil test if you are establishing a new garden, if you have added amendments and don’t know your current fertility level, if you have noticed a decline in productivity, or if it has been more than three years since your last soil test.

Home soil tests are available for prices between $15 and $30. You can get good results from them if you follow the instructions carefully, though laboratory tests are more accurate. If you are using a lab, contact them ahead of time for any special instructions.

To get a useful soil test, you need to collect soil from the rooting area, about 6 to 8 inches deep. Remove any roots, mulch or debris from the samples. Collect soil from at least five different areas in your garden. One way to do this is to sample in a “W” pattern, with a sample at each point. Put your five samples in a clean container and mix them thoroughly. Be sure each collection point is representative of your garden. If different areas have different textures, colors or fertilization histories, they will need separate tests.

A basic soil test will provide pH and levels of nitrogen, phosphorus and potassium, which are the major plant nutrients. Laboratory tests may also provide levels of secondary nutrients, micronutrients, or other tests upon request. Most laboratories will also include fertilizer recommendations.

For best results, base your fertilization program on a soil test. Fertilize several days before planting, incorporate well, don’t overfertilize, and enjoy your garden!

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