Plant Clinic

How can I test my soil?

Taking a sample: Collecting soil for a soil test.
Taking a sample: Collecting soil for a soil test.
Oklahoma State University

Q: My plants are not doing well. How do I test my soil? Can I do it by using a kit or does it need to be done in a lab?

R.T., Miami

A: Soil testing can be done at the University of Florida in Gainesville for a nominal fee but they can only test the pH and phosphorus (which is not a concern since our soils usually have enough to meet plant’s needs) for soils from Miami-Dade County. There are no reliable soil tests for high pH soils.

With very few exceptions, the pH of Miami-Dade County soils is between 7.4 and 8.4. Because of the nature of these soils, the pH can’t be lowered. Therefore, soil testing for our county is a waste of money unless you are testing non-native soils such as vegetable garden soil that has been heavily amended. However, the pH of your vegetable garden soil will rise if you water your garden because of the high pH of our tap and well water. But your vegetables will still grow fine.

Using an over-the-counter soil testing kit is not useful for our soils either.

If you are concerned because your plants are not thriving, often it has little to do with our soils. You should contact your local UF County Extension office for advice (Broward 954-357-5270, Miami-Dade 305-248-3311, ext. 228, Monroe 305-292-4501, Palm Beach 561-233-1700) to have the plant problems identified and to get evidence-based recommendations.

Adrian Hunsberger is an entomologist/horticulturist with the UF/IFAS Miami-Dade Extension office. Write to Plant Clinic, 18710 SW 288th St., Homestead, FL 33030; e-mail

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