food garden with raised beds and wood chip pathways

At Home Soil Testing

Helping the Earth by adding only what is needed
WSU Extension > Snohomish County > MG Home > Educational outreach > Soil Testing
Rows of lettuce are divided by thin black tubing that make up a simple, but effective drip irrigation system for easy watering and water conservation.

Why test your soil?

Master Gardeners often get the question ‘Why isn’t my plant healthy?’
We often answer, “Have you had your soil tested?’
The benefits of a Soil Test:

  • Soil nutrients are not the same across your property
  • Avoid adding unnecessary fertilizer
  • Provides nutrient application recommendations that your soil needs
  • Identifies soil pH and the possible need for liming
  • Shows how soil nutrient changes over the years

Having your soil tested gives you a detailed assessment of your garden soil. The analysis provides the nutrients and quantities needed to make your garden flourish!

Soil Testing Labs

Instructions about how to collect and process a soil sample are on each website.

Try to mail out sample to lab the same day you take it. If mailing at a later date, place sample in the
freezer to stop microbial activity which can cause varied test results, avoid mailing near the weekend.

The Snohomish Conservation District

May provide soil testing, often at no charge under certain circumstances, for property within its district.
Address: 528 91st Ave NE, Lake Stevens, WA 98258
Phone: 425-335-5634
E-mail: outreach@snohomishcd.org
Website: https://snohomishcd.org/

Frequently asked questions:

For annual crops, such as vegetables, test soils when you first cultivate a field or change crops or rotations. If you plant successive crops in a single season, you don’t need to test before each planting.

For perennial crops, such as orchards, tree plantations, alfalfa, grass seed, and permanent pasture, the most important time to test the soil is before planting so necessary nutrients can be incorporated into the soil. If you plan to compare soil test results with the results of a leaf analysis, take samples in August.

In high rainfall areas of western Washington, soils are likely to be acidic and require periodic liming. Testing these soils in the late summer or fall allows time for these amendments to react with the soil before the following growing season.

Soils should be analyzed often enough to recognize potential nutrient management issues before they adversely impact plant growth. In general, test every 2 to 3 years for annual crops, pastures, and legumes, and test every 3 to 5 years for Christmas trees, fruit and nut trees, berries, and grapes. Take samples at the same time of year so results are comparable from year to year.

The area from which to collect a soil sample may depend on the soil type, topography, crops grown, management history, or all of the above. For example, a farm that has three separate sampling areas: A (flower garden), B (lawn), and C (vegetable garden), a separate soil sample should be collected from each of the three areas.