Even though the summer garden season is winding down, there’s still a lot going on. In addition to caring for our plants, many of us are thinking about what we can do differently next year since likely some of our plans worked out and maybe others didn’t work out so well. As we contemplate what we are going to plant next year and where, don’t forget about your soil. After a season of growing, it’s a good time to take a look at the nutrients in your soil. While there are a variety of test kits available online, I tend to rely on the testing lab at OSU for soil test results, and fall is a great time to do a soil test.

Why fall? To answer that question, let’s talk about the 3 primary nutrients we are concerned with in our soil: nitrogen, phosphorus, and potassium. These are the big three nutrients you see referenced on fertilizers in an amazing variety of combinations. Nitrogen in the soil can be fixed pretty easily and quickly because nitrogen is considered a mobile nutrient. A mobile nutrient is one that moves easily in the soil.

Phosphorus and potassium are considered immobile nutrients, meaning it takes them a while to move in the soil and become available for your plants. Because of this, the fall is a good time to do a soil test to check your nutrient levels so that any amendments needed to correct your immobile nutrients have all winter long to work on making themselves available to your plants next spring.

To get your soil tested, you just need a bucket, a collection tool (we have tools you can check out, but a bulb planter or a trowel work well), and a sandwich bag. To collect soil for your soil test, you’ll need to get 15 to 20 soil samples from the area you want sampled. If you want your vegetable garden tested, gather these samples from your vegetable garden. If you would like your lawn tested, gather your 15 to 20 samples from throughout your lawn.

As you collect each sample, be sure to dig down 6 inches because the test is calibrated for a depth of 6 inches. With each sample you collect, drop it in the bucket. When you have all your samples in the bucket, mix it up a bit and remove any sticks, grass, or twigs. Then fill up a sandwich bag with soil from your collection.

Once you have your sample, bring it to the Tulsa County OSU Extension at 4116 E. 15^th Street in Tulsa. You’ll then need to fill out a form and pay the $10 fee for the testing. Be sure to specify whether your soil is from a vegetable garden, flower garden, or lawn since this can affect your recommendation. You’ll receive your results within a couple of weeks.

The good news is that your test results come with recommendations on how to properly amend your soil. Good luck!

You can get answers to all your gardening questions by calling the Tulsa Master Gardeners Help Line at 918-746-3701, dropping by our Diagnostic Center at 4116 E. 15th Street, or by emailing us at mg@tulsamastergardeners.org. Photo: tom Ingram