Many people want a lawn which is completely free of weeds, including dandelions. Before you use herbicides, however, remember that dandelions can be beneficial to your yard and your health. Also, be aware that there are less hazardous ways to kill and remove weeds. This article discusses how to create a healthy lawn and techniques for removing and controlling dandelions.

Benefits

Dandelions can be beneficial to a garden ecosystem as well as to human health. Dandelions attract beneficial ladybugs and provide early spring pollen for their food.(1,2) In a study done at the University of Wisconsin, experimental plots with dandelions had more ladybugs than dandelion free plots, and fewer pest aphids, a favorite food of the ladybugs.(2) Dandelions long roots aerate the soil and enable the plant to accumulate minerals,(3) 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 U.S. 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.(4, 5)

Dandelions are also used as herbal remedies. The white sap from the stem and root is used as a topical remedy for warts. The whole plant is used as a diuretic and liver stimulant.(6)

Identification and Biology

The dandelion is one of the most common and recognizable weeds. The official name for the dandelion is Taraxacum officinale,(7) which means "official remedy for disorders".(4) There are many common names for dandelions, including priest's crown, Irish daisy, monk's head, telltime, blowball, and lion's tooth.(4)

The dandelion is a broadleaf weed, with a deep, fleshy tap root. What looks like a dandelion flower is actually many tiny yellow flowers surrounded by leafy bracts.(8) They are produced on stalks 6 to 40 centimeters tall (2.5 to 16 inches) clustered at the base of the plant.(7)

The common dandelion is a biennial or perennial plant which reproduces by seed.(7) The seeds spread with the help of their downy parachutes.(8)

People often confuse the common dandelion with the false dandelion, Hypochoeris radicata. The false dandelion looks similar to the common dandelion(7) and can be controlled with the same methods.(9)

Prevention

The best defense against dandelions is a healthy lawn,(10) since "a properly maintained lawn is less susceptible to weeds, insects, and diseases."(3) Steps to a healthy lawn include overseeding with the grasses you want to crowd out weed seedlings.(10) Mow frequently and leave the grass clippings on the grass as fertilizer.(10) Set your mower to cut at a height of 2 to 2 1/2 inches.(10) Mowing at shorter heights allows more dandelion seeds to germinate and makes the lawn prone to weed invasions.(11) Don't cut off more than 1/3 of the height of your lawn at a time, especially just before the Northwest's typically dry summer, as this could cause the grass to go into shock.(10)

Avoid over watering; watering deeply and infrequently will build deeper roots and help prevent disease. Northwestern lawns need (on average) an inch of water per week to stay green during dry summers. Lawns on clay soils, or soils rich in organic matter, will only need to be watered once or twice per week. Sandy or gravelly soils will need to be watered more often.(10) For more information on healthy lawns see http://www.pesticide.org/lawns.html.

Physical Control

Decide how many dandelions are tolerable in your lawn, then pull them as necessary. Get as much of the root as possible. Pulling or digging is easiest and most effective when the soil is wet.(10) Dandelions are most successfully pulled when they are small seedlings, before they have developed tenacious tap roots.(12) There are a variety of different pulling tools that make effective dandelion removal easier. See "Tools for Dandelion Removal," (below) for examples of the many different models available.

Cutting the weeds with long handled shears is another method, though it will take more than one time to kill the weed entirely. When cutting, cut lower than the lawn mower and make sure to cut all the leaves and as much of the stem as possible. Repeatedly cutting the greens prevents the plant from getting the nutrients it needs to survive. The root will stop sending up new growth and the plant will eventually die.(13)

A product that uses radiant heat to kill dandelions is the Puzzy Boy. One model (the Puzzy Boy Punto) is designed to kill weeds with long tap roots. The Punto has two thermal elements, one to kill the parts of the plant above the ground, and a spike on the end to kill the roots. Both are heated by a propane burner.(14) Its retail cost is less than $200. 

If you have lots of dandelions in cracks in sidewalks, brick patios, or driveways, you might want to try a flame weeder. Flame weeders are also effective on graveled areas.(10) These tools burn propane from refillable tanks that are carried on a backpack. Hold the flame about 6 inches above the weed for a few seconds. The flame heats the dandelion's sap and bursts the cell walls. Wilting and death occur several hours later.(16)

Least Toxic Chemical Control

There are several least toxic herbicides available. Corn gluten meal is a preemergent weed control product. When applied to turf, it prevents dandelion seeds from sprouting but won't harm plants that are already growing.(17) For more information, see the U.S. Environmental Protection Agency (EPA) factsheet.

Vinegar effectively kills dandelions. Spray it directly onto weed for about three seconds. Be careful though, as vinegar will also kill grass.(18) For more information, see the EPA factsheet.

Other Control Methods

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.(19)

Anecdotal evidence suggests that if you can boil water you can kill dandelions. Pour the boiling water directly onto the weed. Boiling water kills any vegetation it touches, so be careful where you pour it.(20)

Conclusion

Remember that dandelions can be beneficial. Be willing to put up with a few dandelions in your yard. If you need to control dandelions, focus on creating a strong, healthy lawn. By maintaining a healthy lawn, you will eliminate the need for other time consuming controls. If necessary, there are many nonchemical tools available to kill dandelions or remove them from your lawn.

TOOLS FOR DANDELION REMOVAL

(from left to right)

The Weed Hound
A 32" long tool with a plunger type rod which forces six prongs through holes in a metal plate. It uses a foot pedal to remove weed.
http://www.hound-dog.com
(800) 694-6863

Weed Popper
A 40" long foot lever. Pushing down on lever forces tines into ground, which pops out weed.
http://www.faultless.com/gardening_products.html
(800) 821-5565

Dandelion Weeder A specialized weed puller with a 36" long handle.
http://www.ames.com/rightTool/weedingTools.html
(800) 5334-9326

Eco-weeder 
A machine that uses radiant heat to kill dandelions.
http://www.chemfree-weedcontrol.com
(604) 534-9326

Weed Dragon
A tool that uses a propane flame to kill weeds. Recommended for dandelions growing in gravel or sidewalk cracks.
http://www.FlameEngineering.com
(800) 255-2469
 

References

1. Klass, C. and M.P. Hoffman. 1996. Attracting insects' natural enemies. Ecogardening factsheet #14. Cornell Univ. Dept. of Horticulture. http://www.cce.cornell.edu/programs/hort/gardening/factsheets/ecogardening/attracten.html.
2. Harmon, J.P. et al. 2000. Coleomegilla maculata (Coleoptera: Coccinellidae) predation on pea aphids promoted by proximity to dandelions. Oecologia 125: 54-548.
3. Hill, S.P. and B. Walsh. 1992. Ecological lawn maintenance. EAP Publication - 68. Ecological Agriculture Projects, McGill University. http://www.eap.mcgill.ca/Publications/EAP68.htm.
4. Mattern, V. 1994. Don't weed em eat em. Organic Gardening 41(4):70.
5. U.S. Dept. of Agriculture. 2001. USDA nutrient database for standard reference. www.nal.usda.gov/fnic. (Query for dandelion greens, raw.)
6. Ody, P. 1993. The complete medicinal herbal. New York, NY: DK Publishing, Inc., p. 103.
7. Gilkey, H. M. 1967. Handbook of northwestern plants. Corvallis, OR. Oregon State University Bookstores, Inc. p.472.
8. Dalby, R. 1999. The delightful dandelion. American Bee Journal 139: 300-301.
9. Clemson Univ. Cooperative Extension Service. Undated. Clemson Extension garden center: Broadleaf weeds. http://hgic.clemson.edu/factsheets/HGIC2301.htm.
10. Mcdonald, D.K. 1999. Ecologically sound lawn care for the Pacific Northwest. Seattle, WA: Seattle Public Utilities.
11. Hummel, N.W. 1990. Lawn care without pesticides. Cornell Cooperative Extension Home and Grounds Fact Sheet, Nov.
12. Olkowski, W., S. Daar, and H. Olkowski. 1991. Common-sense pest control. Newtown, CT: The Taunton Press, p. 482.
13. Schultz, W. 1989. The chemical-free lawn. Emmaus, PA: Rodale Press, p. 127.
14. Forevergreen Chemical Free Weed Control. Undated. Punto. http://www.chemfree-weedcontrol.com/products/punto.shtml.
15. Personal communication with Wingren's Landscape Maintenance, Inc. Bolingbrook, IL, Aug. 20, 2001.
16. U.S. EPA. Region 9. 1997. IPM for schools: A How-to manual, Mar. p. 142.
17. Bingaman, B. R., McDade, M.C. and Christians N.E. 2000. 1995 corn gluten meal rate weed control study - year 5. 2000 Iowa Turfgrass Research Report. http://turfgrass.hort.iastate.edu/pubs/turfrpt/2000/cgmrate.html.
18. Morris, C. How to have a dynamite lawn. http://www.ciscoe.com/lawns/lawnout.pdf
19. TIlman, E.A. et al. 1999. Biological weed control via nutrient competition: Potassium limitation of dandelions. Ecol. Appl. 9:103-111.
20. Metro Regional Services and Oregon Dept. of Environ. Quality. 1998. Natural gardening: A guide to alternatives to pesticides, p.48. http://www.metro.dst.or.us/metro/rem/garden/pestalt.html.