Skip to Content

Kill Crabgrass Without Killing Grass: How to Do It [2023]

This site is supported by our readers. We may earn a commission, at no cost to you, if you purchase through links.

Are you looking for a way to kill crabgrass but not grass? Achieving this goal requires understanding the physiology of crabgrass and taking control with the right products.

At Pennington, we provide you with what is needed in terms of quality lawn and garden products along with expert advice to help get your desired weed-free lawn.

Crabgrass is an opportunistic annual weed that will grow in thin spots on your lawn, so it’s important to take preventative measures before germination occurs. Pre-emergent herbicides target seeds while post-emergents target actively growing plants — both are necessary steps for killing off existing crabgrass without harming surrounding grass or other vegetation.

Timing plays an essential role when controlling these weeds as does mowing at proper heights, feeding regularly, deep watering, and repairing any damages done by pests or weather conditions.

Combination herbicides can also be used alongside fertilizers if deemed necessary; however, safety measures should always be taken into consideration before usage begins.

Key Takeaways

how to kill crabgrass but not grass

  • Timing is crucial when controlling crabgrass, and pre-emergent herbicides should be applied in early spring before germination starts.
  • Selective post-emergent herbicides can effectively target and kill existing crabgrass plants without harming other desirable grass.
  • Maintaining a healthy lawn through proper mowing, fertilization, and deep watering can help prevent crabgrass growth.
  • Combination herbicides and lawn fertilizers can create a hostile environment for crabgrass while promoting the health of the grass.

What is Crabgrass?

What is Crabgrass?
You already know that crabgrass is an opportunistic weed, but did you also know that it produces thousands of seeds and can quickly spread in warm, dry conditions?

Crabgrass preventers like Pennington UltraGreen Crabgrass Preventer plus Fertilizer III 30-0-4 help stop the germination of these pesky weeds.

Soil temperatures must be at least 55°F for four to five days before applying pre-emergent herbicides. Timing is key – they must be applied prior to seed germination as post-emergent products are ineffective against preventing new growths.

Selective herbicides target only certain plants or categories while nonselective kill all plant types; combination fertilizers and weed killers generally won’t harm lawn grasses so long as directions are followed carefully.

Actively growing crabgrass requires a selective post-emergent product such as Image All in One Lawn Weed Killer or Image Herbicide Kills Crabgrass for best results.

Furthermore, mowing your lawn short may not stop the spreading of existing seeds so proper maintenance practices such as feeding regularly and deep watering should be implemented to discourage their growth by making turf thicker and less welcoming towards them altogether!

How to Kill Crabgrass?

How to Kill Crabgrass?
Once the soil temperature reaches 55°F, pre-emergent herbicides are an effective way to prevent crabgrass from sprouting. Post-emergent herbicides can be used to kill existing plants, while selective products target specific weeds or categories of plants without harming other grasses.

Carefully read labels and follow instructions when using any type of weed and feed product, as some lawns may be more susceptible than others.

Pre-Emergent Herbicides

Pre-emergent herbicides can help keep crabgrass away by preventing its seeds from germinating. Application should correspond with soil temperatures of 55°F, and weed control for lawns must target specific plant categories to be effective.

Pennington UltraGreen Crabgrass Preventer plus Fertilizer III 30-0-4 is an example of a pre-emergent herbicide that prevents the establishment of new crabgrass plants, as well as other broadleaf weeds.

Post-Emergent Herbicides

Once crabgrass is already established, post-emergent herbicides can be used to control it. Selective targeting of specific weeds or plant categories is effective against actively growing plants up to 150,000 seeds per! Product labels must be consulted for the best results, and lawn fertilizer products generally won’t kill crabgrass.

Soil temperatures are important in determining when these treatments should occur, as well as which grass varieties may be susceptible to certain herbicides. Crabgrass preventers provide an effective way of controlling this warm-season annual weed while protecting other desirable turf species and following safety precautions.

Selective Herbicides

For optimal control of crabgrass, it’s important to select the right type of herbicide. Timing and lawn preparation are crucial when targeting weeds like this warm-season annual.

Pre-emergent products should be applied before soil temperatures reach 55°F for four to five days in order for seed germination to occur.

Selective herbicides target specific weed seeds or plant categories, while non-selective ones kill all plant types, including your lawn grasses.

Combination products generally won’t work against crabgrass problems, so read labels carefully and follow instructions accordingly.

Timing Crabgrass Control

Timing Crabgrass Control
To ensure successful crabgrass control, timing is critical and needs to be done before the weed’s tiny seeds germinate like a summertime blanket.

The optimal spray timing for controlling crabgrass depends on soil temperature and the amount of bare spots in your lawn. Pre-emergent herbicides should be applied in early spring when soil temperatures reach 55°F for four or five days.

Post-emergents can then be used in late summer to kill existing plants, while selective products target specific weeds without harming other grasses.

Pennington UltraGreen Crabgrass Preventer plus Fertilizer III 30-0-4 continues to prevent crabgrass along with other broadleaf weeds, as well as providing nutrients needed by your lawn throughout the season when kind of stress is experienced due to extreme weather conditions like drought or heavy rainfalls.

Scotts® Turf Builder® Halts® Crabgrass Preventer helps protect new grass from emerging seedlings while feeding it at the same time – making it an ideal solution if you plan on seeding this year!

Read product labels carefully and follow instructions. Applying pre-emergents too soon could inhibit the future growth of newly seeded areas, so wait at least 60 days after application before overseeding areas treated with a preventative herbicide such as Pennington UltraGreen Crab Grass Preventer Plus Fertilizer III 30 0 4.

How to Prevent Crabgrass?

How to Prevent Crabgrass?
Maintaining a healthy lawn is an important step in preventing crabgrass growth. Proper mowing, regular fertilization, and deep watering are all essential for creating an unfavorable environment for the weed’s germination.

Additionally, repairing any damage to your lawn can help keep it free of invasions from unwanted plants like crabgrass.

Mow at the Proper Height

Maintain a healthy, lush lawn by mowing at the proper height, and you’ll help to discourage crabgrass from taking over. Tall grass blades create deep roots and increase resistance to damage caused by common lawn weeds.

Fertilize with turf builder or other types of lawn food for an extra layer of protection against weed growth while also providing essential nutrients for your full lawn.

Deep watering encourages root growth that can strengthen the entire yard’s defenses against crabgrass invasion! Herbicide safety is key when applying pre-emergent treatments; ensure directions are followed closely as incorrect use may cause more harm than good!

Feed Regularly

Feeding your lawn regularly with a quality fertilizer like Scotts® Turf Builder® will help ensure a lush, strong grass that’s better able to resist the spread of crabgrass. Proper fertilizing and watering can boost growth by up to 50%, while mowing regularly prevents germination of low-growing crabgrass seeds.

To patch damage, use products such as Scotts EZ Seed Patch & Repair following spring applications, and always read label instructions for safe application of herbicides, including broadleaf weedkillers, when establishing new grass.

Deep Water Your Lawn

Deep-watering your lawn on a regular basis encourages strong, deep root growth, making it less inviting for weeds. It is important to monitor water depth and soil temperature when applying pre and post-emergent herbicides or feed fertilizers.

A general rule is to use a premium product and water frequently for the best results. Before applying any products, use a digging knife to dig deeper into the soil. This will ensure optimal absorption of nutrients while controlling crabgrass germination in your lawn throughout the season.

Repair Lawn Damage

Repairing bare spots in the lawn helps keep out unwelcome weeds, so fill those gaps with a patching product like Scotts® EZ Seed® Patch & Repair. Overseeding will also help control crabgrass and other weeds; use a hand trowel to prepare soil for overseeding.

Weed control products must be applied before yellow-blooming forsythia shrubs appear in late winter/early spring. To ensure optimal results, choose specific preventer products and apply them according to label instructions when soil temperatures reach 55 °F or above.

Use spot treatment products as necessary throughout the season, but always read labels carefully first before using any product on your lawn!

Combination Herbicides and Lawn Fertilizers

Combination Herbicides and Lawn Fertilizers
Combining herbicides and fertilizers can help create a hostile environment for crabgrass, so it’s important to read product labels carefully and follow instructions.

Pre-emergent weed resistance products like Pennington UltraGreen Crabgrass Preventer plus Fertilizer III 30-0-4 are effective at controlling crabgrass before the seed germinates. Proper application of these products is essential for success. They must be applied prior to soil temperatures reaching 55 degrees Fahrenheit for four or five days in order for them to work properly.

Post-emergent herbicides may also need proper timing depending on the type used. Consideration of other factors such as fertilizer types, weather conditions, and lawn health is necessary before applying them.

Different prevention strategies should be considered when dealing with an existing single crabgrass plant or bare spots in your lawn. These may require more aggressive approaches like spot treatments with Image All-In-One Lawn Weed Killer or Image Herbicide Kills Crabgrass.

These products target specific weeds while leaving tall grass blades unharmed due to their selective nature.

Ultimately, maintaining a healthy lawn by following optimal care practices such as deep watering and regular feeding will help inhibit infestations from occurring.

Safety Measures for Herbicides and Weed & Feeds

Safety Measures for Herbicides and Weed & Feeds
When using herbicides or weed & feed products, always make sure to take safety precautions for the best results. Read and follow product labels carefully. Some lawn grasses may be more susceptible to certain herbicides than others.

Selective post-emergent herbicides can target specific weeds while leaving other plants unharmed, whereas non-selective ones kill all plant types that come into contact with them.

Crabgrass works best with selective post-emergent herbicides as it is actively growing during that time of year. If unattractive weeds are present in thin patches on your lawn areas where crabgrass preventer has been applied, consider spot treatments with ready-to-use products before germination starts in mid-spring when soil temperatures reach 55°F or higher for four consecutive days.

Utilizing optimal care practices such as deep watering and regular feeding will help create a thick and lush environment less welcoming towards any invasions from unwanted plants like crabgrass! Keep these tips in mind when trying to control this pesky weed without harming the rest of your beautiful lawn!

Frequently Asked Questions (FAQs)

Is there an effective organic solution to killing crabgrass?

Discover the power of organic solutions for killing crabgrass! Each plant produces up to 150,000 seeds, and pre-emergent herbicides can prevent germination. Selective post-emergents target specific weeds for effective control without affecting grasses.

What is the difference between pre-emergent and post-emergent crabgrass control?

Pre-emergent control prevents crabgrass from germinating, while post-emergent is used to kill existing plants. Applied before the soil reaches 55°F, pre-emergents stop seeds from sprouting. After that temperature is reached, post-emergent herbicides are necessary for the destruction of already growing weeds.

How long does it take for crabgrass preventers to start working?

Crabgrass preventers take effect quickly, usually within a few days of application. Maintaining optimal lawn care practices is key to maximizing the efficacy of these products for long-term control.

Can I overseed my lawn after applying a crabgrass preventer?

Wait at least 60 days and two mowings after applying a crabgrass preventer before overseeding your lawn. This will allow the herbicide to take full effect and give your seeds the best chance for success.

Does mowing the lawn high or low make a difference in controlling crabgrass?

Mowing your lawn high and low can both help in controlling crabgrass. High mowing encourages deep root growth, while low mowing reduces the amount of sunlight to weeds like crabgrass.


To effectively kill crabgrass while preserving your lawn, it’s important to use the right pre-emergent and post-emergent herbicides. Timing is key when applying these products. It’s better to prevent the spread of crabgrass than to try to get rid of it once it has taken hold.

Additionally, proper lawn care practices can help prevent crabgrass from taking over. This includes mowing at the correct height, fertilizing, and watering deeply. Remember the old saying, An ounce of prevention is worth a pound of cure.

Avatar for Mutasim Sweileh

Mutasim Sweileh

Mutasim is a published author and software engineer and agriculture expert from the US. To date, he has helped thousands of people make their yards lush and thick.