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

What is diatomaceous earth?

Diatomaceous earth, or diatomite, is a soft sedimentary rock that is  easily crumbled into a near-white powder. It consists of diatoms, the  fossilized remains of a special group of ocean-floating single-celled  organisms, commonly known as phytoplankton. As a powder, diatomaceous earth can  be used as an insecticide. The fine powder absorbs lipids from the waxy outer  layer of insects' exoskeletons, causing them to dehydrate. Because of the  drying and absorbing power of the powder, diatomaceous earth can also be used  on the ground around plants to discourage snails, slugs and crawling insects.  Diatomaceous earth can also be used indoors to control cockroaches, ants,  silverfish, crickets. millipedes, centipedes, fleas, carpet beetles and  bedbugs.

Natural diatomaceous earth is virtually nontoxic to man and other  mammals, but it can cause extreme nasal irritation if inhaled. The kind of  diatomaceous earth used as a filtering agent in swimming pools, however, has  been heat treated and contains crystalline silica. It is a definite respiratory  hazard, leading to possible silicosis, and should not be used in the garden. Read and follow all label directions and safety procedures.