What to do with the bevy of broadleaf weeds flowering in lawns
Dandelions, violets and ivy, oh my! Many weeds are currently flowering in turfgrass, but not all require control.
In the last week, dandelions have been lighting up the landscape with their brilliant yellow flowers. In most areas, the first flush of dandelion flowers has come and gone, and now the puff-ball stage is in full effect. According to Michigan State University Extension, applying a herbicide at the puff-ball stage can be very effective, as this is the time the dandelion is at its weakest because it has just spent all that energy pushing out flowers. Applications prior to puff-ball stage can be effective at burning down the rosette and preventing puff-balls, but keep in mind that if you really want to get ‘em, schedule a fall application.
In addition to dandelions, many other broadleaf weeds are flowering in turf right now. Common chickweed, henbit, shepherd’s purse, yellow rocket, corn speedwell, wild violet and ground ivy are all flowering. All but wild violet and ground ivy are winter annuals. The life cycle of a winter annual is they germinate in fall, overwinter and then flower and produce seed in spring. After flowering in spring, winter annuals are usually only two to three weeks from dying.
If you apply herbicides now, they will be dead and gone in two to three weeks. If you do nothing, they will be dead and gone in two to three weeks. Get it?
Similar to the strategy of controlling dandelions, there are some very tough-to-control weeds that are also flowering right now. Ground ivy (also known as Creeping Charlie), wild violet and several speedwells (Germander and Creeping) are actively flowering. The flowering period is the best opportunity to kill them until fall arrives. The typical broadleaf combination herbicide containing 2,4-D provides fair control at flowering, but if you can find combination herbicides with the active ingredients quinclorac, triclopyr, fluroxypyr or carfentrazone, you should achieve better than fair control.
Dr. Frank's work is funded in part by MSU's AgBioResearch.