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.

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Horticulture Questions and Answers

When should I lime my lawn?

Lime should not be applied to a lawn in the St. Louis area unless you’ve had the soil tested and the pH is below 6.0.

The parent rock of most St. Louis soils is limestone which already has a very high pH and provides plenty of lime in the soil.

Too much lime in the soil can raise the pH to a level that is harmful to many plants, including turfgrasses. An optimum range for most cool season turfgrasses is from 6.0 to 6.8.

For a small charge, soil tests can be done at the Missouri Botanical Garden's William T. Kemper Center for Home Gardening or University of Missouri Extension. See “How do I test my soil?”

Follow rate and application information provided with the soil test results. If liming is recommended, pelletized products are easier to apply than ground or pulverized limestone.

If establishing a new lawn, be sure to have the soil tested prior to seeding the lawn. If lime is needed, apply it before working the soil. Rototill to a depth of five to six inches deep. Lime moves down into the soil slowly so mixing the lime into the soil is more effective than just spreading the lime over an established lawn.

Lime may be added in the spring or fall and can be applied at the same time as other fertilizer products.