How to Get an Accurate Garden Soil Test

An accurate soil test can let you know ahead of time if your blue hydrangeas may turn pink.

Before planting in any new garden you should determine whether soil is acidic or alkaline, has enough organic matter or needs fertilizer, or is heavy clay or nutrient-poor sand. A garden center pH kit or electronic meter does not tell the whole story, investing a few dollars in a real soil test through your local cooperative extension service is well worth the time and money to any gardener.

Things You'll Need

• Clean garden shovel
• Clean gloves
• Clean bucket
• Paper towels
• Zipper-top bags
• Permanent marker
• Large, padded manila envelope

Instructions

1. Survey your garden (veggie plot or flower beds). Select 12 different locations around this garden to collect samples from.

2. Put on your gloves -- cross contamination is the biggest enemy to a soil test. Ensure your tools are clean and you don't touch any soil with your bare hands, which can also contaminate the sample.

3. For each of your 12 samples, dig down 8 inches into your soil with a shovel. Bring out a good scoop, about 1 to 2 cups of soil and dump the soil in your clean bucket. All 12 samples go into the same bucket. Keep your gloves on and use your clean tools to mix the 12 soil samples together.

4. Lay out a thick layer of paper towels in a dry, draft-free workspace, like a screen porch or garage. Spread out 2 cups of your soil mixture onto the paper towels. Let the soil air dry overnight.

5. Put your gloves back on the next day. You'll need to collect 1 cup of air dried soil and place it in a clean zip-lock bag. Label the bag with your name, address, and phone number. Give the soil sample a name -- veggie beds, rose garden or new house -- and write that on the bag for reference.

6. Fill out a soil testing form from your local university cooperative extension service. Fill it out, pack up your samples, and send it off.

Tips & Warnings

• I recommend at least the "C. Standard soil test with organic matter" for every soil sample. It's $13.

• The "D. Soil texture test" is expensive but really worth it for new gardens.

• The "E. Soluble salts" is a good test to get for new lawns.

• Your soil test plots can be as small as a single garden or you can take one test for your entire yard (still using the 12 samples). I like to have separate samples for lawns, vegetable beds, and flower beds.

• I love the UMASS soil testing, I send my samples for the West coast. It's really accurate, easy, fast, and the prices are good.

• Keep your hands and tools squeaky clean for the most accurate testing results.

References

• Virginia Cooperative Extension: Soil Sampling for the Home Gardener
• North Carolina State University Extension: A Gardener's Guide to Soil Testing

Resources

• U.S. Department of Agriculture: Cooperative Extension Service Offices