Gardening Help FAQs

Here are answers to some of the most common questions we receive about garden plants. You will find concise information on general gardening techniques as well as plant selection and care. For detailed information on specific plant pests and problems refer to our Common Garden Pests and Problems page.

Do you have additional gardening questions? Please contact us. Here's how.

Horticulture Questions and Answers

How do I test my soil?

A soil test is the best way to determine the level of nutrients available in your soil. Test results will tell you the amount and type of nutrients your plants need. The test also measures the soil pH, that is, how acidic or alkaline your soil is. You can also request tests for micronutrients.

Soil test results depend on how well you take the soil sample. The sample should reflect the overall lawn or garden condition. Make a representative sample by collecting small amounts of soil from various spots within the planting or growing area. Take soil from at least 3 places in areas less than 500 square feet. Take 5 samples from areas between 500 and 1,000 square feet. Use a clean shovel or garden trowel to take thin slices or cores of soil. The depth should be 3 inches for lawns and 4-6 inches for gardens. Break up the soil and mix thoroughly. You need about two cups of dry soil for each test.

You can take soil samples any time the ground isn't frozen. Late fall and early spring are good times to have your soil tested. Take representative samples from each area you want analyzed. See "Soil Testing and Sample Collection"

Since plants have different nutrient needs, separate tests should be done for lawn and garden areas. You may even want to take separate tests for the front and back yard or shady and sunny areas. More representative samples result in more accurate recommendations.

Put each soil sample in a clean plastic bag, labeled with your name, address and the sample location. Make a record of the areas of the lawn or garden each soil sample represents.

You can get your soil tested through the William T. Center for Home Gardening (314-577-9440) at the Missouri Botanical Garden. The Center for Home Gardening is located in the Garden, about a 5 minute walk from the Garden entrance at 4344 Shaw Boulevard. Center Hours are 9 a.m. to 5 p.m. daily. Results of the tests will be e-mailed or mailed to you in 10 to 14 days. The basic test measures pH, organic matter, phosphorus, potassium, calcium and magnesium. The fee per sample for a basic test is $22.00 for garden members, $24.00 for non-members. The complete test measures all of the basic nutrients plus six micronutrients. The complete test is $33.00 for members, $36.00 for non-members.

The Plant Doctor at the Center for Home Gardening will assist you if you need help interpreting your test results or you can call the Horticulture Answer Service with your questions.