Weed control
Weed control for Kansas City lawns
Most weed problems here are timing problems. Crabgrass is decided by mid April, dandelion and clover in the fall. A June spray on either one mostly misses.
Weed control is available in Missouri. In Kansas I offer core aeration, seeding, fertilization, and leaf cleanup.
Timing beats product
A pre-emergent does nothing to crabgrass that is already up. It sits in the top of the soil and kills seedlings as they germinate, so it has to be down before germination starts. Miss the date and most preventers do little for the rest of the year.
Perennial broadleaf weeds run the opposite way. Dandelion, white clover, ground ivy and plantain spend the fall moving reserves down into their roots, and a herbicide applied then rides down with the flow. The same spray in May hits a plant pushing everything upward, and you can get a burnt top over a live root that grows back.
Nutsedge is neither. It is a sedge, with a triangular stem, growing from nutlets under the ground, and K-State notes that ordinary crabgrass and broadleaf products have little or no effect on it. It needs its own chemistry, in summer, at the three to eight leaf stage before this year's tubers form.
The dates that decide the year
- Soil in the low to mid 50s for about five daysThe pre-emergent trigger. K-State puts crabgrass germination at about 55 F an inch down for five days, so the preventer has to beat that. MU says to apply once the soil holds between 50 and 55 F for five days running.
- Late March into mid April, most yearsThat is the window Johnson County Extension gives for getting a preventer down here, and the K-State timing map puts the Kansas City area in the April 15 band. In any given year the soil thermometer decides.
- Redbuds in full bloomThe you-are-late signal. K-State says get the preventer down before redbuds reach full bloom.
- Late September into early NovemberThe best stretch of the year for dandelion, clover, ground ivy and plantain, because the plant is loading its roots for winter.
- Summer, for nutsedge onlyDifferent weed, different product, treated young at three to eight leaves rather than chased all season.
How an application goes
- I look at what is actually growingThe K-State efficacy table rates a common three-way product good on dandelion and plantain and not effective on wild violet, where triclopyr is the one that works. Reading the lawn first is the difference between a result and a repeat visit.
- The weather picks the day65 to 80 degrees is the target for a broadleaf application. Above 85, or on drought-stressed turf, it does more to the fescue than to the weeds. No rain or irrigation for 24 hours after.
- Spot or blanket, whichever the lawn earnsA dozen dandelions is a spot job. A lawn that is a third clover is not, and pretending otherwise wastes a trip.
- I follow the labelEvery product is EPA-registered. Rate and timing come off the label on the container, and so does how long to keep off the grass afterward.
- Watered in when the label calls for itA pre-emergent needs about half an inch of water within three days or it sits on the surface doing nothing.
What an application will not fix
These get sold as weed control around here, and the usual spray does not work on any of them. Each one needs its own plan.
- Established bermudagrass in a fescue lawn. K-State: there are no products that give good selective control of it. The route is glyphosate on actively growing bermuda, more than once, then replanting.
- Nimblewill, the dull brown scouring-pad patches that stay brown while the fescue greens up. K-State lists it under weeds that cannot be selectively controlled. Selective options are argued about; the reliable fix is the same as bermuda.
- Wild violet with a standard three-way product. It is rated not effective. Triclopyr gets rated good on violet and ground ivy, and it will take more than one round.
A seeded lawn changes the schedule
New seed and broadleaf herbicide do not mix in either direction. K-State says do not apply broadleaf products within four to six weeks before seeding, and not after seeding until the new grass has been mowed three times. MU puts the pre-seeding wait at three to four weeks. Where they disagree, take the longer number.
In practice a lawn seeded in September gets its broadleaf application in late October or November. Johnson County Extension calls late October through early November the most effective time of the year for broadleaf control anyway.
The winter annuals are what you give up that year. Henbit and chickweed germinate in fall, and their pre-emergent belongs down around mid September, right on top of new seed. On a lawn being seeded I leave it off and deal with them in spring.
Questions I get
Do you use chemicals?
Yes. Weed control means applying EPA-registered herbicides according to the label on the jug. I will tell you what went down and when. If a lawn company cannot answer that question about your own yard, that is the thing to push on.
Why will you not spray in July?
Heat, and biology. Above 85 degrees or on grass already stressed by drought, a broadleaf application punishes the fescue. Perennial weeds are not moving anything toward their roots in July either, so the timing is wrong twice over.
I paid for crabgrass preventer and still have crabgrass.
Usually it went down after germination started, or the residual ran out. Pendimethalin is the short one and wants a second round about six weeks later. Prodiamine at a full rate can carry past six months. There is also a post-emergent that works on young crabgrass, best at one tiller or less.
Will one visit clear it up?
Annuals, often. Perennials, usually not. K-State rates the common three-way products only fair on clover and ground ivy, and nutsedge is known for needing repeat applications.
Weeds fill the gaps a thin lawn leaves
Thick turf crowds weeds out, and thin turf hands them the ground. Feeding at the right time of year does more for weed pressure over a season than any extra spray does.
Get a quote for weed control
Send the address and say what you are looking at, or send a photo of it. I will tell you what it is and when it should be treated, and the price comes back in writing.