Clover: Here's what to do with those white flowers in your lawn
Q. Mike: How do I get rid of an abundance of clover in my yard? I have a small grandson and I worry about all the bees the clover is attracting. Thanks,
- ---Dottie in Patchogue, Long Island, NY
- ---Nancy in Hopkinton, Massachusetts
- ---Bob in Fredericksburg, Virginia
- ---Frank in Lyons, IL; "All dogs look up to you. All cats look down on you. Only the pig looks at you as an equal." –Winston Churchill
Anyway, clover is obviously a big issue in many areas this Spring. But it's a NON-issue in some others, explains YBYG turf grass expert extraordinaire, Dr. Nick Christians, Professor at Iowa State University and the man who discovered that nitrogen-rich corn gluten meal prevents weed seeds from germinating at the same time as it feeds the turf.
"You must be having a wet Spring", correctly declared Nick when I told him that lots of Philadelphia area lawn owners were also complaining of clover. "You stole our rain", he accused, adding that Iowa has been very dry, and therefore has very little clover. "Clover LOVES water," he explains. So that's lesson #1: Don 't help it out; resist the urge to water your lawn early in the season if you dislike the white flowers.
Nick adds that if you are growing a cool-season grass, a heavy Fall feeding of corn gluten meal—20 pounds per 1,000 square feet—will virtually eliminate the problem over several years time. Now, we always recommend using corn gluten in the Spring on cool-season lawns to prevent crabgrass and other dormant weed seeds from sprouting. But we generally suggest compost for the larger Fall feeding that cool-season grasses like Kentucky blue require—to add organic matter and improve the soil underneath that turf.
But Nick tells us that applying corn gluten instead (around mid-August in most areas) has a double benefit. "The pre-emergent activity will prevent any seeds those flowering tops have produced from germinating," he explains, and in the third year of multi-year studies at Iowa State, clover and dandelions were almost completely eliminated in plots that were fed corn gluten meal twice a season—with no physical or chemical weed removal!
(Nick sent us some pretty amazing pictures of those plots and the untreated areas adjacent to them—click here to see clover, and here for dandelions.
Dr. Trey Rogers, prestigious professor of turfgrass science at Michigan State University and "Yard Doctor" (www.yarddoctor.com) spokesperson for Briggs & Stratton, isn't surprised that big feedings of corn gluten defeated the clover at Iowa State, because clover "is a tell-tale sign of an underfed lawn. Clover is a legume that can convert nitrogen in the air into plant food", he explains, "so it's not dependant on fertilization. But regular grasses can't do that. So when a lawn goes hungry in the Spring, the well-fed clover takes over". He also agrees that cool, wet Springs would produce the worst (or best, depending on your point of view) crops of clover, because many forms of nitrogen need a soil temperature of 60 degrees or more for microbes to make them available.
Which helps explain why Fall feeding would be so important; a turf that wakes up well fed is going to better out-compete clover. Long term, it's also going to help develop thick roots that can crowd out weeds. (As we vegetable gardeners know all too well, grass is the most tenacious 'weed' there is!) "And never scalp your lawn when you cut it," adds Trey. "Set your mower higher, and cut more often. Just taking off little bits of grass at a time really increases the density of the turf and crowds out all kinds of weeds."
Trey's colleague, Michigan State Environmental Turf Grass specialist Ron Calhoun agrees, and says that their long-term studies of corn gluten meal mirror the Iowa State results: "Heavy feeding of cool-season grasses with corn gluten meal in the Fall virtually eliminates clover over a three or four year period." Using CGM in the Spring may directly help as well, he adds. "As Trey explained, some forms of non-chemical nitrogen, like manure, can take a long time to become bio-available in a cool Spring. But plant based sources, like corn gluten meal, seem to be less temperature dependant."
And those immediate concerns about bees? They do love clover, but contrary to many people's expectations, don't enjoy stinging us. The researchers we spoke with work extensively around clover and all said they've never been stung. Most stings attributed to bees are actually caused by wasps, like the highly aggressive yellowjacket, which isn't active in the Spring. And most true bee stings happen accidentally—like when people step on one barefoot or brush up against one in a swimming pool. Kids who wear something on their feet—and don't try and grab the buzzers—are unlikely to get stung. And don't forget—those bees will greatly increase the number of flowers in your garden.
If that's not enough reassurance—or if someone is severely allergic—use a flame weeder like the Bernzomatic "Outdoor Torch" to singe the white flower heads; no flowers, no pollen, no bees.
Or collect the flowers when they first open and eat them! Garden writer Sally Roth, in her 2002 book "Weeds; friend or foe?" explains that white clover, a Native plant, was an important food for indigenous Americans. High in protein, vitamins and minerals, the sweet and fragrant young blooms were dried, crushed into flour and added to a variety of foods, including stews. She adds that two tablespoons of dried white clover flowers also makes a fine throat-soothing tea.
Or just mow it down as soon as the flowers open; you won't spread any seed, and all the nitrogen those pretty white blooms have sucked out of the air will feed your nitrogen-hungry lawn naturally, which, in the long run, will also reduce future infestations.