We had a great class at the Morton Arboretum last Friday, and while we were planning front gardens for all 20 students, we got into talking about soil testing. Everyone in this class has a new build or a mature landscape that has been long in need of a spruce up! Both of these scenarios require a soil test to know how to care for the soil. After all, in a sustainable garden, it's the soil that nurtures the plants.
Soil tests can be simple or very complex, and what you choose to do should depend on your specific questions. We typically recommend a high level lab test if you have never had one done and you want to know about the overall health of your garden soil. On the other hand, if you are only testing for lead content in an area where you plant to do edible gardening, less expensive tests are available. Finally, if you want to do a simple test on your own, you can buy a do-it-yourself kit at your garden center.
Proceed as follows: Select an area where you want the soil tested. This should be one garden bed or an area not bigger than 150 sq. ft. And remember tat the topsoil is what you are testing -- the darkest and topmost area in the cross-section shown above. Dig down about 4 inches in 3 or 4 spots in the area you want tested, and take a half cup or so of soil from each. Mix well and place a total of about 2 cups of the mix in a PAPER bag. Seal the bag and place in a mailing box. Send this to the lab. If you need to test other areas, send a sample in this fashion for EACH area you want tested.
You can find reputable labs on Google, or by checking with your local garden center or conservation associations. Sage Advice can also recommend soil test agencies.