Crabgrass is an invasive annual that can overpower and choke out a stressed turf. A single crabgrass plant can drop thousands of crabgrass seeds, and when the soil temperatures rise in the spring, they can take off and out-compete damaged lawn grasses. As an annual weed, a mature crabgrass plant will die after dropping thousands of seeds every year.
It is not necessary to let crabgrass seedlings overtake your lawn but knowing when crabgrass emerges and when it dies can help you plan for proper lawn maintenance to ensure a healthy lawn. Crabgrass infestation can happen quickly, but healthy turfgrass can handle the task, read on to find out when crabgrass dies and how to keep it out of your lawn.
When Does Crabgrass Die?
Unlike broadleaf weeds that may persist for years, crabgrass germination happens in the spring, and by winter, the plants are finished their life cycle. Most of the dead plants will have dropped seeds that will germinate by late spring when soil temperatures have risen, and water is available. Crabgrass will die every winter when nighttime temperatures drop below 32 degrees, and your soil experiences its first frost.
Crabgrass can also die in drought or extreme summer weather conditions. While typically able to thrive in hot summers, extended time in the shade or unusually cool temperatures can kill off crabgrass seedlings. Keeping healthy lawns mowed high to prevent sunlight on the soil can kill crabgrass at any time of the year.
What Kills Crabgrass Permanently?
Grassy weeds can be tricky, but it is possible to eliminate crabgrass from your entire lawn. We all want a healthier lawn, but lawn grasses can be tricky, and soil health can degrade without us knowing it. In case your lawn has started to show more and more weeds each year, use these lawn care services for an amazing lawn all year round.
| Treatment | Effects | Reapplication |
| Pre-Emergent | Stops common lawn weeds from germinating | Once per season |
| Post-Emergent | Kills common lawn grass weeds and selectively treats invasive grasses | Every 8 weeks as needed |
| Lawn Care | Promotes the growth of desirable lawn grasses, can repair lawn damage, and makes for a more weed-resistant lawn | Spring and fall fertilizing with summer and winter maintenance |
Pre-Emergent Herbicides
Commonly known as crabgrass preventers, these pre-emergent herbicides cover the ground and prevent crabgrass germination. Crabgrass preventer products should be used by mid-spring by the latest before soil temperatures have risen to 55 degrees or higher. Inexpensive soil thermometers can help you apply lawn treatments at the ideal time.
The majority of crabgrass weeds produce root toxins that affect the root development and root systems of your turf grass. To protect your lawn’s grass from crabgrass, you will want to apply a comprehensive lawn care program that fights weeds before they sprout. Crabgrass is common along the edges of lawns or where lawn damage has occurred, so reseed with grass seed and apply lawn fertilizer to help crowd out existing crabgrass sprouts unaffected by the pre-emergent herbicides.
Post-Emergent Herbicides
Dead crabgrass plants might still drop seeds, so it is important to treat surviving weeds before late summer. A healthier lawn will have less of a need for post-emergent herbicide products, but it is good to check the entire lawn for patches of crabgrass. Selective herbicides that can kill mature weeds but not harm your turf grass are readily available for broadleaf plants but harder to find for aggressive lawn weeds.
Check safety precautions when applying non-selective herbicides, or your green lawn could suffer some lawn browning and invite further pest and weed problems. Poor lawn maintenance will lead to large patches of weeds, and regular inspections can keep outbreaks to a minimum. Make sure to apply weed killer before crabgrass drops its seeds in the fall and lay down pre-emergent in the early spring for year-long control.
Lawn Care Services
Lawn care companies can help you maintain your lawn during seasons of extreme stress, but the overall health of your lawn must be monitored year-round. Lawn fertilizer products, lawn grass seed, and weed treatments are needed for a lush, healthy, weed-free lawn. A thicker lawn is less susceptible to weeds than a sparse thinning turf.
Mowing and watering schedules are two of the most important aspects of lawn care and have the biggest impact on overall turf health. Lack of water, shallow watering, and a low cutting height can all lead to weak and weed-prone turf. Crabgrass does not grow tall like other turfs and cannot tolerate shade, so letting your lawn grow tall and watering when conditions are dry can prevent large areas of weed growth from cropping up.
Tips to Deal With Crabgrass on Lawns
While it is very easy for crabgrass seeds to make it onto your lawn from neighbors, birds, and other carriers, it is not necessary for them to find fertile ground to grow. By following the tips below, you can help reduce the chance that your lawn will succumb to invasive weedy grass species like crabgrass.
Avoid Scalping
Areas of lawn along walks and paths can easily be scalped by mowers and weed eaters. Without a proper edge, it is easy to hit the turf at an angle that cuts the lawn shorter than the selected mower height. The damage can quickly lead to bare earth, heated soil, and germination of pesky weeds.
To avoid scalping, mow the perimeter of the lawn first and give yourself space to whip and edge. When following the mowing with weed whacking, stand on solid surfaces and not in the grass to prevent dips and low cuts. Push mowers onto the lawn with the blades off and only activate cutting when the wheels are level to keep the turf even along the edges and sides.
Use Correct Fertilizer
Most lawn fertilizer brands offer spring and fall options. Spring fertilizers usually have high nitrogen formulas that are quickly released to aid in the rapid spring growth period. Fall fertilizer is more likely to have high levels of potassium for deeper root growth and a slow-release nitrogen component that will be available in the spring.
Using fast-release fertilizer in the fall can promote cool-season weed growth to run rampant while your turf becomes dormant in winter temperatures. A fall fertilizer used in the spring may not give your turf the boost it needs and could aid warm-season plants in the summer when your turf slows down from drought or heat. Promote turf growth by giving your grass the right nutrients at the right time, and you will have far fewer weeds to deal with.
Mow at 3 Inches or Higher
Crabgrass grows prostrate and occupies bare and exposed areas of our lawns. In order for it to thrive, the roots and soil need direct sunlight and ample heat. Keeping turf grass high and shading the soil at all times makes it hard for crabgrass to spread. A good mower height for most turf types is 3 inches or higher.
Since crabgrass dies off in the winter, it is okay to mow your turf lower for the winter months to help focus on root growth and keep grass blades strong during dormancy. Make sure not to damage the turf with dull blades or expose any earth, or you may invite more weeds in the spring.
Supplement Water in Early Spring
Crabgrass thrives when turf begins to dry out and can germinate quickly if water is given in late spring. Lawns that are water-starved will be unable to stop crabgrass from running rampant. Begin supplementing water in the early spring when the soil is still warming up to give your grass a head start before crabgrass has a chance to germinate.
If you wait until your lawn looks dry in the late spring to water, you will be giving weeds exactly what they need while not necessarily providing your turf with the amount of moisture required to thrive. Dry and underfed lawns will be heavily affected by weeds like crabgrass in early summer and need to be treated and maintained immediately and repeatedly.
Reseed in Spring and Fall
Bare soil is the quickest way to invite weeds into your lawn. Exposed earth is common after summer drought and winter cold. Applying grass seed after weather extremes and before dormancy can improve your lawn’s health tremendously.
Apply grass seed in the spring along with fertilizer and steady watering. Make sure to time any pre-emergent application until after grass seed sprouts have fully emerged in the spring to avoid killing new growth. A fall application of grass seeds can be sprouted and mulched in preparation for cold winter weather. Any turf growing in bare spots will reduce the areas weeds can take root, so plant grass seed whenever lawn soil is exposed.