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Ask the Ecologist-June 2008

by Belle Bergner Q: I’ve always followed my neighbors’ lead in plucking dandelions every spring and summer, but are dandelions truly bad for lawns? A: The “perfect turf” people of the world will not be pleased with my answer, but it is true: dandelions can be beneficial to a garden ecosystem as well as to human health. Although dandelions are not native to Wisconsin or North America, neither is the grass that makes up your lawn. Dandelions attract native and beneficial ladybugs that eat garden pest aphids, providing early spring pollen for their food. Dandelions’ long roots also aerate soil and enable the plant to accumulate minerals, which are added to the soil when the plant dies. Not only are dandelions good for your soil, they are good for your health. According to the US Department of Agriculture, a serving of uncooked dandelion leaves contains 280 percent of an adult’s daily requirement of beta carotene, as well as more than half the requirement of vitamin C. Dandelions are also rich in vitamin A. Dandelions are used as herbal remedies: the white sap from the stem and root is used as a topical remedy for warts, and the whole plant is used as a diuretic and liver stimulant If you still want to rid your yard of dandelions, the best defense is a properly maintained lawn that is less susceptible to weeds, insects, and diseases. You can overseed with the grasses you want – that will crowd out dandelion and other weed seedlings. Mowing properly can also help – mow frequently and leave the grass clippings on the grass as fertilizer. Set your mower to cut at a height of 2 to 2 1/2 inches. Mowing at shorter heights allows more dandelion seeds to germinate and makes the lawn prone to weed invasions. If you are still inclined to pull dandelions up, try to get as much of the taproot as possible. When placed just a half inch or so below the soil surface, a simple weeding tool can effectively pry up most of the root. There are several non-toxic herbicides available. Corn gluten meal prevents weed seeds from sprouting but won’t harm plants that are already growing. Vinegar also effectively kills dandelions. Spray it directly onto the plant for about three seconds. Be careful to avoid spraying the vinegar on surrounding grass because it will kill that, too. Avoid fertilizers that contain potassium (one of the nutrients in many lawn fertilizers). Long-term studies in the United Kingdom found that potassium fertilizers increased dandelion densities up to 20-fold. In conclusion, if you are willing to put up with some dandelions, you can take care of most of them with some good yard care and non-toxic yard maintenance. Send your ecological inquiries to our resident ecologist at