Your experience of winter will vary depending on your location in the country, so your weed-targeting strategy will have to match the type of weather you’re experiencing, as well as the weeds showing up in your yard.
In the northern US, winter weeds can still grow in the frozen February ground under the snow. In transitional states, the wet weather will encourage weed growth while the grass is dormant. In places where the weather gets damp and cold, winter weed management can be a bit of a challenge, but with the right tactics, undesired growth can be eliminated.
Winter Weeds
When your grass goes dormant in winter, some weedy plants will take advantage of the free ground space. The coldest months are actually an excellent opportunity to use weed killer on your lawn since your grass is out of the way for the season. Types of winter weeds include:
- Broadleaf weeds – Dandelions, chickweed, and plantains are common broadleaf winter weeds. These plants have wide, flat leaves and can be managed by spot-treating them when you see them growing or using a granular herbicide across the lawn.
- Clover – Clover is a low-to-the-ground creeping plant that spreads quickly to cover an area. Although this is a weed when it’s in your lawn, some people like to let this grow in the winter and till it into the soil for a green spring fertilizer. If you want your lawn to regrow after the winter, a granular fertilizer treatment will be the best option since spot-treating clover would be too difficult.
- Grass weeds – In transitional areas, some warm weather grasses that tolerate cooler temperatures, like pau annua and crabgrass, can show up during the cool and wet winters. Since your cool-season grass is dormant, a plant-specific herbicide should be used to eliminate any grass weeds growing amongst your lawn.
How Do You Control Weeds In The Winter?
Your cold-season weed control should begin even before winter does. If you’re not seeding your lawn this autumn, you can apply a pre-emergent herbicide in late summer or early fall to suppress any weeds that might show up during the high-growth transitional season.
If you are applying new grass seed in the fall, you shouldn’t use herbicides until the beginning of winter because they can interfere with the germination process.
Through the freezing temperatures, rain, and snow, it seems like it will be challenging to find the right conditions to apply herbicide during the winter. When done at the right time, however, spray weed killers can be effective for spot-treatment of your lawn when you see greenery popping up through the dead grass.
For all-over treatment, grass-safe granular herbicides can be applied across the yard at the end of fall or beginning of winter. These are best delivered in combination with fertilizer, like weed and feed products do, to prepare the soil for the upcoming spring regrowth of your grass.
When Is It Too Cold To Spray A Herbicide?
For most liquid herbicides, an application will work best when temperatures are above 50 degrees. When they reach below that, several factors decrease their effectiveness.
For example, roundup will not work at 50 degrees and should only be used when nighttime temperatures don’t dip below that threshold. Since roundup can’t be sprayed in winter, there are other options to consider to deal with unwanted weeds in the winter months.
This doesn’t apply to all kinds of herbicides in cold weather, however, notably in the case of granular weed killer, specially formulated liquid sprays, and organic options like vinegar and mulch cover.
When Should I Spray Winter Weeds?
Liquid weed killer shouldn’t be applied when it’s wet out. Dry, non-windy conditions are the best if you need to spay during the winter months. Wetness can dilute the spray since moisture is present on the leaves, and it can be easily washed away in either rain or snow.
That being said, weeds should be sprayed as soon as you can after seeing them because the bigger they get, the more resilient they can be to the spray. This is especially true when it’s cold because their cell walls are more restricted to protect the plant from moisture loss.
When the weed is in its growth period, it will absorb the weed-killer moisture better despite the cold, destroying the leaves, stems, and root system before it can spread.
Vinegar On Winter Weeds
If you’re interested in an organic option for spot-treating cool-weather growth, vinegar will kill weeds in the winter. You should take caution when applying vinegar on your lawn for weeds in any season because it isn’t selective, meaning that it can damage any plant, including grass if too much is used.
Since you want the weed to soak up the herbicide through its roots and leaves, you have to use enough vinegar to kill the weed by reapplying it every couple of days until it is destroyed. This can be effective to spot treat a few weeds, but it isn’t a great option for lawn-wide protection.
Applying Weed And Feed In Winter
Weed and feed products can be used at the end of fall or the beginning of winter, applied to moist ground before the soil freezes, and suppress any weed growth throughout the season. While spray herbicides can be easily washed away, the granular herbicide in weed and feed products uses the moisture in their favor to be soaked into and distributed throughout the soil.
The fertilizer component to weed and feed products will also be soaked up by the ground, conditioning the soil for spring with nutrients and a clean slate for grass growth.
Applying Mulch Or Compost
Using mulch and/or compost on your lawn during the winter after your grass has gone dormant will help suppress weed growth over the season. A layer of organic material on the topsoil will create a barrier that blocks light from reaching the soil surface, keeping potential weeds from germinating and sprouting.
Mulch and compost will also condition the soil over the winter as it is incorporated into the topsoil. The organic material slowly decomposes and releases nutrients over the next year, and your grass will benefit from nutrient-rich soil for healthy green growth as the weather warms up.