America’s Most Weeded: Dandelions Back »


Fall is the best time to control broadleaf weeds like dandelion.


Weed Profile

Dandelions (Taraxacum officinale) are probably one of the most noticeable and common lawn and field weeds of all. Just about everyone that has a lawn has fought to get rid of this weed at one time or another. They are very adaptable to the types of soils in which they will grow, can tolerate repeatedly being mowed off to within a couple inches of their lives yet seem to thrive in countless lawns and other non-cultivated areas throughout the northern Great Plains, most of the United States with related species found all over the world. This low-growing member of the Aster (Asteraceae) family produces bright yellow-orange flowers on hollow stems about 3 to 8” long, depending on where it is growing. Each plant may produce a few dozen flowers over the course of a growing season with peak bloom usually in early summer but flowering can continue into mid-summer or even into the fall. Each of those individual flowers may produce dozens of individual seeds, each equipped with a silky little parachute of white fibers that are designed to allow the seed to be carried off by the wind or when blown by a child.

Dandelion is a perennial weed that develops a deep taproot within just a few weeks. Only basal leaves are produced because the flowering stems do not possess any leaves. All parts of the plant contain a white, bitter sap. The leaves are elongated, and grow to about 1” wide and 5 to 6” in length with distinctive serrations and dissections in the leaf giving them a jagged appearance, similar to the teeth of a lion, for which it is named. As plants age over several years, leaves may become more upright, particularly if they are growing in tall grass, among other plants or in shadier locations. But in a lawn situation, the leaves tend to remain fairly close to the ground.

One of the amazing things I have noticed about dandelions is their ability to come back after mowing. Even though one might try to time mowing to when there are at what seem to be a maximal number of flowers sticking up in the grass of the lawn, the next day there appear to be nearly as many back in their place. Those flower stems must grow very rapidly – perhaps mowing off the other flower stems on a plant somehow stimulates the remaining flower stems to grow that much more quickly. Individual flowers are open for only a few days but providing a significant food source for bees and butterflies during that time. In a couple of weeks the flowers reopen to expose the ripened seeds, each with its own silky parachute to help distribute the seeds.

Management

Controlling dandelions can be a challenge. Once plants are a year old or more, they have likely stored up significant food reserves in their fleshy tap roots so they can withstand stressful conditions for some time. However, they are not that competitive against a thick, dense lawn. A dense lawn makes it more difficult for new dandelion seedlings to get established and the grass blades block sunlight from the leaves of the dandelion plant. Raising the mowing height to at least 2 ½” is also helpful in promoting healthy grass and increasing the competition for dandelions and other lawn weeds.

Most people think about trying to control their dandelions in the spring when they see them in bloom. However, this is not the best time to try to control them, particularly if they plan to use a broadleaf herbicide to do it. Dandelions are in their most active growth stage in the spring and are actually somewhat resistant to the herbicide at that time. Yes, you can curl up the flower stems and the leaves a bit but will probably not really kill that many dandelion plants at that time of the year. Another larger concern is that there are so many other broadleaf plants actively growing at that time of the year too, most with lots of soft, succulent foliage that will easily take up the herbicide. The result is damage to trees, shrubs, perennial flowers and often garden vegetable plants. The new growth will become twisted and the new leaves will be misshapen and pinched. Since there are no stated safe levels of herbicide residue in garden vegetables like tomatoes or potatoes, the fruit produced from drift damaged plants may not be safe to eat. Dry, granular weed and feed products that contain a fertilizer as well as a broadleaf herbicide may be somewhat safer than a liquid herbicide because it is less likely to drift. But the efficacy of a weed and feed product may not be as good, particularly if it is not applied correctly. Be sure to follow the label directions for whatever product you decide to use.


Dandelions are generally quite easy to control with a fall herbicide treatment.

Fall treatment of dandelions is a much better option for a number of reasons. First of all, dandelion plants are much more susceptible to the effects of the herbicide in the fall. They are actively storing carbohydrates in their roots which makes it easier for the herbicide to be translocated to the roots as well. Secondly, plants of all ages will be susceptible. Spring treatments will not affect the seed that is flying around at that time of the year. Once that seed lands, it starts the next generation of plants that will have avoided the spring herbicide application. So, the next spring, dandelions will still be there in the lawn. Treating in the fall is much more likely to break the cycle of new plants growing up from seed because there are usually only a few flowers forming in the fall. Secondly, most other broadleaf plants are shutting down for the year in the fall. In fact it is not a bad idea to wait until you start seeing the leaves of your trees and shrubs turning their fall colors before you treat for dandelions and other broadleaf weeds. Once the leaves on your trees start turning color they will be much less likely to absorb broadleaf herbicides from drift and have it translocate to other parts of the plant. The vegetable garden is also shutting down for the year, particularly if you delay your herbicide application until after the first frost. While most garden vegetables will be damaged by the frost, dandelions are cold tolerant enough that they can withstand freezing temperatures and still be susceptible to control with herbicides. As long as they are still green, you can probably still spray.


Dandelion diggers can be used to help control dandelions.

Hand digging of dandelions is another method of control, but really only feasible in a small yard situation. There are a number of different types of dandelion diggers available, most of which are designed with a narrow shaft with a broader, forked tip that can cut the root or pry the plant up out of the soil. Keep in mind that the fleshy tap root may go down a foot or more into the soil. An older plant can be difficult to dig out. The tap root may be a ½” in diameter, 12” long and may even have a few branches off the main root. If you do not dig it all out, there is a good chance that new shoots will develop around the remaining portions of the root and the dandelion will regrow, often with several smaller plants taking over where the larger, original plant once grew. Dandelion digging a few days after a good rain can make it easier to get most of the root out. It can also be rather therapeutic and you can work on it over several weeks, eventually clearing out the dandelions in your lawn or garden. Hand digging is probably the only good option when dandelions are growing in a flower bed too, since you should avoid trying to use herbicides amongst other plants.

Other Uses

Dandelions are not all bad however. I have fond memories of taking a basket out into the pasture back home on my parent’s dairy farm in Wisconsin to collect dandelion flowers for my grandmother to make dandelion wine. I recall how she put them in a big crock to ferment with a dish towel over the top. I do not remember how the dandelion wine tasted however, probably not very good to a young child of eight or so. Dandelions can also be eaten, particularly in the early spring when they are not too bitter tasting. The young leaves as well as the crown of the plant can be used in salads. The leaves are often blanched to reduce the bitter flavor. The roots can be dried and ground up to make a coffee substitute. The roots are sometimes used as a component of root beer. Dandelions are credited with various medicinal properties as well.

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