Don’t use Tenacity on a Bermuda Grass Lawn, Unless….

Generally speaking, Tenacity is an herbicide that will, at the very least, curb the growth of Bermuda grass, if not kill it. It should not be used on a Bermuda grass lawn that you want to thrive. Let’s dive into what Tenacity is and how it should be applied.

Can You Use Tenacity on Bermuda Grass?

Tenacity should not be used on a healthy, thriving bermuda grass lawn if you want it to survive. However, there is one case where you can apply it safely: when the Bermuda grass is dormant. Bermuda grass generally goes dormant when soil temperatures drop below 55°F. Depending on where you are, that’s generally between late fall and mid-spring

However, if your goal is to limit bermuda grass growth, Tenacity can selectively control bermuda grass without harming other desirable grasses. However, it’s important to follow all instructions carefully and apply the herbicide at the right time of day to avoid any potential side effects, such as bleaching of susceptible bermuda grass. It’s also important to note that while Tenacity can suppress Bermuda growth, it may not completely eradicate it and other herbicides may be more effective for long-term control.

What is Tenacity and How Does It Affect Bermuda Grass?

Tenacity is a herbicide that can selectively control weeds, including most types of Bermuda grass. It works by inhibiting photosynthesis, which can cause the plants to turn white or yellow.

Tenacity is a pre and post-emergent herbicide, meaning it can control both existing weeds and prevent new weeds from germinating.

Tenacity herbicide’s active ingredient is mesotrione, which belongs to a class of herbicides called HPPD inhibitors. Mesotrione works by inhibiting an enzyme in plants that is necessary for chlorophyll production, which is essential for plant growth and photosynthesis. As a result bermuda grass treated with Tanacity will be unable to produce enough chlorophyll, which causes it to become bleached or discolored, and potentially die.

Because bermuda grass is not producing chlorophyll in the dormant season, however, Tenacity has negligible effects on it during that time.

Tenacity’s Effect on Other Grasses

Mesotrione, the active ingredient in Tenacity, is designed to attack broadleaf weeds, not grasses. It will certainly stunt the growth of all plants that produce chlorphyl, including grasses, but there are other herbicides that are better for grasses, such as bluegrass, fescue, and zoysia grass.

If you’re trying to kill a foreign grass in your lawn, consider mixing Tenacity with another herbicide that targets grasses rather than broadleaf weeds. Usually, the most Tenacity will do, especially in a cool season application, is bleach the foreign grass and curb its growth temporarily. But it will usually recover.

A Useful Video on Mixing Tenacity with Other Herbicides

Why use Tenacity on a Dormant Bermuda Grass Lawn?

You would find Tenacity useful on a bermuda grass lawn if it has gone dormant, and there are other undesired cool-season weeds growing within your bermuda grass lawn.

Tenacity herbicide is most effective at killing or controlling a wide range of broadleaf weeds, including both perennial and annual weed species. Some common weeds that Tenacity can effectively target and control include:

  • Crabgrass (Digitaria spp.): Both smooth crabgrass (Digitaria ischaemum) and large crabgrass (Digitaria sanguinalis) are susceptible to Tenacity.
  • Dandelion (Taraxacum officinale): Tenacity can effectively control dandelions, which are perennial broadleaf weeds known for their yellow flowers and puffball seed heads.
  • White Clover (Trifolium repens): Tenacity is effective against white clover, a low-growing perennial weed with small white flowers and three-leaf clusters.
  • Ground Ivy (Glechoma hederacea): Also known as Creeping Charlie, ground ivy is a persistent and aggressive perennial weed that Tenacity can target.
  • Purslane (Portulaca oleracea): Tenacity can help control this succulent annual weed known for its thick leaves and small yellow flowers.

Note that while Tenacity is effective against these weeds, its efficacy may vary depending on the specific weed species, growth stage, and environmental conditions. It is always recommended to read and follow the instructions on the product label for the best results and to ensure the safe and proper use of Tenacity.

Crabgrass – a common weed Tenacity is effective on

Identifying Weeds in Your Bermuda Grass Lawn

If you have a Bermuda grass lawn that has gone dormant and you notice the presence of cool-season weeds, it’s important to properly identify the specific grass species before considering the use of Tenacity or any other herbicide. Here are some steps you can take to identify the cool-season grasses and assess their susceptibility to Tenacity:

  • Visual Identification: Observe the growth habit, leaf shape, texture, and color of the cool-season grasses. Compare them to common cool-season grass species like Kentucky bluegrass, fine fescue, or perennial ryegrass. Field guides or online resources with images can assist you in the identification process.
  • Consultation: Seek advice from a local extension office, a knowledgeable lawn care professional, or a horticulturist to help with grass identification. They can provide specific information about the prevalent cool-season grasses in your region and offer guidance on eradication methods. Facebook groups can be great for this too.
  • Small-Scale Test: Before applying Tenacity to the entire lawn, perform a spot treatment test in a small, inconspicuous area. Apply Tenacity as directed and observe the response of both the Bermuda grass and the cool-season grasses over a few weeks. This will help you assess the effectiveness and any potential damage to either grass species.
  • Research Tenacity Efficacy: Consult the product label or reach out to the manufacturer to determine if Tenacity is effective against the identified cool-season grasses. The label or manufacturer’s recommendations may specify the grasses it targets and provide guidance on application rates and timing for optimal control.

Remember, it’s crucial to follow all label instructions, including recommended rates and application timing, to minimize any potential damage to desirable Bermuda grass or unintended consequences for your lawn. When in doubt, seeking professional advice specific to your region and grass types is always a good idea.

Bermuda Grass Mixing with The Neighbor’s Lawn

Often homeowners face a problem of dueling lawns. You have your Bermuda, but your neighbor has Kentucky Bluegrass that creeps into your lawn every winter & early spring. In this case, the use of Tenacity would also help to curb the growth of Kentucky bluegrass or any other cool-season turf that might be encroaching.

Just be sure that your bermuda grass is, in fact, dormant before you apply Tenacity. If your bermuda has entered into the early stages of growth, you run the risk of stunting it as well as the intruding grass.

How to Use Tenacity for Weed Control in a Bermuda Grass Lawn

If you want to use Tenacity on your lawn, it’s important to follow the instructions carefully. Tenacity should be applied in the late fall, winter, or early spring when the Bermuda grass is dormant, and it should not be used on newly seeded lawns. It’s also important to avoid applying Tenacity during hot and dry weather.

Applying Tenacity herbicide to bermuda grass during high temperatures can be particularly damaging, increasing the risk of grass burn. High temperatures can cause grass to become stressed, making it more vulnerable to damage from herbicides like Tenacity.

When applying Tenacity herbicide to a lawn, it is important to follow the instructions provided on the product label. Here are some general guidelines for applying Tenacity:

  • Timing: Apply Tenacity when the target weeds are actively growing, but avoid applying during periods of stress, such as high temperatures or drought conditions. For Bermuda grass, apply Tenacity when it is dormant.
  • Mixing: Mix Tenacity with water according to the recommended rates provided on the label. The appropriate dilution ratio may vary depending on the specific application and target weeds.
  • Equipment: Use a sprayer or other suitable application equipment to apply Tenacity evenly over the lawn. Ensure that the equipment is clean and properly calibrated to achieve accurate and consistent coverage.
  • Application: Apply Tenacity evenly, taking care to cover the target areas without excessive overspray. It is important to avoid applying Tenacity to desirable plants or grasses that may be sensitive to the herbicide.
  • Post-application: Allow sufficient time for Tenacity to take effect. The timeline for visible effects on weeds may vary depending on the species and conditions. Follow-up applications may be necessary for complete control, as directed by the product label.
  • Safety: Wear appropriate protective clothing, such as gloves, goggles, and long sleeves, during mixing and application to prevent direct contact with the herbicide.

Always refer to the specific instructions and recommendations provided by the manufacturer on the product label for detailed information on rates, application techniques, and safety precautions. Additionally, consider consulting with a lawn care professional or contacting your local extension office for guidance tailored to your specific lawn and weed control needs.

Afternoon heat and Tenacity don’t mix

Summertime Weeding in Bermuda Grass

You may be faced with a situation where you are in the middle of summer, your bermuda is thriving, but you have weeds. Should you apply Tenacity in this scenario?

No. While Tenacity can be effective in controlling weeds in Bermuda grass, there are other herbicides that may be more suitable, such as glyphosate or 2,4-D. These herbicides can be used during the growing season, but they should be used with caution and according to the instructions.

In mid-summer you’re better off applying a weed and feed to your bermuda grass. This will promote your bermuda

I have a full article on weed killers for a bermuda grass lawn you can check out for more information.

Tenacity & Bermuda Seed

Tenacity has a negative effect on seeds and seedlings. If you’re planning to seed Bermuda grass, it’s important to wait 2 to 4 weeks after applying Tenacity to avoid damaging the new seedlings.

If you notice weeds in the area where you are planting bermuda grass seeds, you want to eradicate the weeds first. Pick them if you can or apply Tenacity if that’s what you have.

An even better option is to apply a bermuda grass weed and feed before you plant your seeds. This will kill undesired weeds and leave a fertilizer for bermuda grass that will help the seedlings take root.

Overseeding Bermuda Grass & Tenacity

Bermuda grass is known for its aggressive growth and ability to spread rapidly, which can help it outcompete other grass species, including Kentucky bluegrass. Overseeding with bermuda grass can indeed help crowd out unwanted grasses like Kentucky bluegrass, especially if the bermuda grass is well-established and actively growing.

Overseeding Bermuda grass

An especially effective technique of overseeding, would be to apply Tenacity to an invasive cool-season grass in the early spring while the bermuda grass is still dormant, followed by an overseeding of bermuda grass mid-season. This would help crowd out a weakened intrusive cool season grass with seedling bermuda grass.

When overseeding with bermuda grass, it’s important to consider the following:

  • Timing: Bermuda grass should be overseeded during its peak growing season, typically in late spring or early summer when soil temperatures are consistently above 65°F (18°C). This ensures optimal germination and establishment of bermuda grass seed.
  • Preparation: Before overseeding, it’s essential to prepare the lawn properly. This includes mowing the existing grass low, dethatching if necessary, and aerating the soil to improve seed-to-soil contact.
  • Seed selection: Choose a high-quality bermudagrass seed suitable for your specific region and growing conditions. Selecting the right cultivar can ensure better competitiveness against other grasses.
  • Seeding rate: Follow the recommended seeding rate provided by the seed manufacturer. Using the appropriate amount of seed will help achieve adequate coverage and density.
  • Watering and maintenance: Proper watering and maintenance are crucial for successful overseeding. Keep the soil consistently moist but not saturated during the germination period. Follow a regular fertilization and maintenance schedule to promote bermudagrass growth and discourage other grass species.

While overseeding with bermudagrass can help suppress other grasses, it may not completely eliminate them. Persistent weeds or grasses may require additional targeted herbicide treatments or manual removal to achieve effective control.

It’s important to note that the effectiveness of overseeding in crowding out unwanted grasses can vary depending on factors such as local climate, soil conditions, existing grass species, and maintenance practices. Consulting with local lawn care professionals or extension offices can provide tailored advice specific to your region and lawn conditions.


Here are some frequently asked questions related to Tenacity and bermuda grass.

Can I use Tenacity on Cool Season Turf?

Tenacity can also be used for weed control in cool-season turf, such as Kentucky bluegrass and perennial ryegrass. However, it’s important to avoid using Tenacity on warm-season grasses, such as Zoysia and St. Augustine, as it can cause severe damage.

What Grasses Does Tenacity Kill?

Tenacity can kill a wide range of weeds, including crabgrass, bentgrass, and clover. However, it can also kill desirable grasses, such as Kentucky bluegrass, if not used correctly.

How Long After Applying Tenacity Herbicide Can the Grass be Cut?

It’s recommended to wait at least three days after applying Tenacity before mowing the grass. This will give the herbicide time to absorb into the plants and to start working.

Can I Spray Tenacity After Mowing?

It’s best to wait at least a day or two after mowing before applying Tenacity. This will give the grass time to recover and to absorb the herbicide more effectively.

It’s important to remember that Tenacity alone may not completely eradicate Bermuda grass, but it can suppress its growth and allow other grasses to thrive. For best results, Tenacity should be used as part of a comprehensive lawn care plan that includes proper mowing, fertilization, and watering.

What time of day is best to apply Tenacity on Bermuda Grass?

It’s also important to apply Tenacity at the right time of day. The best time to apply is in the morning when the dew has dried but before the sun is too high in the sky. This will ensure that the herbicide is absorbed properly by the grass and doesn’t evaporate too quickly.

What if I accidentally apply Tenacity to Bermuda Grass?

It’s important to note that Tenacity can bleach susceptible bermuda grass, causing it to turn white or yellow. This is a temporary side effect and the grass will recover over time, but it’s important to be aware of this before using the herbicide.

To avoid bleaching, be sure to follow all instructions carefully and apply the herbicide at the right time of day. If you do experience bleaching, don’t worry – it’s a common side effect and your grass will recover with time.

What is the best weed killer for bermuda grass lawns?

There are a number of weed and feed fertilizers that are great for bermuda grass lawns. Weed and feeds target unwanted weeds with an herbicide, while promoting growth to the bermuda grass with a fertilizer.