By John Wilson, Extension Educator
The old saying goes, “April showers bring May flowers” so my question to you is, what do May flowers bring? I’ll let you think about that one for a couple of minutes! I don’t know that it’s the kind of May flowers most people hope for, but April showers certainly have generated calls about purple flowers in lawns.
Unfortunately these are flowers homeowners don’t want. These are found on our number one lawn weed problem, ground ivy! I think one of my Extension co-workers says it best when she states, “Ground ivy is a very horrible weed.” There’s a small fortune, probably a large fortune, to be made if someone could just find a good use for this weed.
Ground ivy is a perennial broadleaf weed, meaning that it comes back from the roots year after year. This plant is the one that grows low to the ground and sends out runners, has scalloped leaves like a seashell, and has a small purple flower. It also has square stems and smells like mint when you mow over it because it is a member of the mint family.
People want to control it now because it is turning their lawns purple, but this is very difficult at this time of year. The major flow of energy and nutrients in the plant in spring is from the roots, where it was stored overwinter, to the above ground portion of the plant. Broadleaf herbicides applied at this time of year may burn the top growth and slow it from spreading, but they rarely give satisfactory control.
The optimum time to apply selective herbicides, those that kill broadleaf plants but not the grass, is in mid-September to mid-October when there is adequate moisture and warm temperatures. The plant is making and storing food for next year’s growth. Good growing conditions at this time cause the plant to translocate the herbicide to the roots, providing better control. The good thing about treating then is, this is also the best time to control other perennial broadleaf lawn weeds like white clover and dandelions.
Even when you apply a selective herbicide in the fall, you will not achieve 100% control with a single application. You will have better results with two applications about three weeks apart in the fall with the second application spot treating weeds that survived the first application. Remember, to be effective, the plants need to be actively growing to metabolize the herbicide.
The other herbicide alternative at any time of year are nonselective products containing glyphosate (or Roundup) which will kill everything, weeds and grass, and then you would need to sod or reseed. So it is best to only use this in the spring or fall if you are going to reseed the area. If you are going to sod an area, you have a little more flexibility on when this could be done.
Remember, using a non-selective herbicide is a last resort measure when there is not enough grass to try to salvage by using a selective broadleaf weed killer. If you have an area that is going to require this drastic measure, I would recommend the herbicide treatment rather than trying to use tillage to control the ground ivy. You might think you have everything killed with tillage, but little root fragments may resprout and you’ll find you have ground ivy coming up in your new seeding.
A couple of other quick reminders. If you haven’t put on your crabgrass preventer this spring, now is a good time to do that. It is good to apply it before a rain. The rain will dissolve and activate it. If you miss out on the rain, you need to water it in with a quarter to a half inch of irrigation… which might seem really strange after all the rain we’ve had recently.
And speaking of rain, if it prevented you from mowing your lawn in a timely fashion, set your mower on the highest setting if it isn’t there already. Then do your next couple of mowings a day or two earlier than you normally would so you remove a smaller percent of the leaf area which will help the turf recover.
Now, for the answer to my earlier question, “What do may flowers bring?” Any elementary student studying U.S. history would be able to give you the answer. Pilgrims! That’s all for today. For more information on controlling ground ivy or other lawn weeds, contact your local Nebraska Extension office.
Kat Country Hub 
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