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.

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Horticulture Questions and Answers

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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". Here is a good video by Nathan Brandt of MU Extension on how to take a soil sample in your yard or garden. How to Take a Soil Sample.

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 University of Missouri Extension. Click here for a flyer that gives you sample collection information, drop-off locations in St. Louis and the fee for a basic test. As of this writing the fee was $22 for a basic test.

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.