How Long Before Tenacity is Rainproof

Photo of author

Written By: Mark Marino

a Massachusetts Core Applicator License holder and owner/operator of Lawn Phix,

Updated on

No comments

No AI pledge. Authored and reviewed by Mark, not robots. Learn more.

If you buy something from one of our affiliate links, we may earn a small commission at no extra cost to you. I've used these products and provided an honest opinion on every product I review. This helps support our site and its free content, lawn care guides, and calendars. Learn more.

Tenacity Herbicide is a unique herbicide. Not only can it kill over 40 weeds, including crabgrass and creeping bentgrass, but it also acts as a pre-emergent. In fact, the active ingredient in Tenacity – Mesotrione – is the only herbicide that can be safely applied at the time of seeding and overseeding your lawn to help prevent weeds for up to three weeks.

Being such a special product, there’s comes lots of questions – from application rates for both pre-emergent and post-emergent applications to irrigation, watering, and knowing how long before Tenacity is rainfast. This post should quickly clear up and answer these questions.

Also, be sure to read our detailed Tenacity Herbicide Review, and try out our Tenacity Calculator.

Tenacity for Pre-emergence

Tenacity Herbicide needs to be watered in when being used as a pre-emergent. According to the label, Tenacity needs to be watered into the soil with 0.15 inches of water within 10 days of application. Thus, if Tenacity is being used to prevent crabgrass and other weeds at the time of seeding, then Tenacity is rainproof immediately after application.

To use: apply 0.11 – 0.18 ounces of Tenacity per gallon per 1,000 square feet. Do not use a non-ionic surfactant (NIS). Water in immediately with 0.15 inches of irrigation or rainfall.

Do not apply Tenacity to newly germinated grass plants for at least 30 days after seed germination, or 2-3 mowings – whichever is longer.

Tenacity for Post Emergence

According to the makers, Syngenta, Tenacity should be rainfast one hour after application. However, for best results, use with a non-ionic surfactant (NIS) and do not water (irrigation or rainfall) a minimum of six hours after applying Tenacity. The herbicide needs time to stick, dry, and penetrate the plant in order to eradicate the weed.

To use: apply 0.11 – 0.18 ounces of Tenacity per gallon per 1,000 square feet. Use with 0.25 ounces (or 1.5 teaspoons) of non-ionic surfactant (NIS). Do not water (irrigation or rainfall) for at least six hours after application.

Please refer to the label as these rates will vary between grass type – particularly Turf Type Tall Fescue (higher rates) and Perennial Ryegrass (lower rates).

How long after application is Tenacity rainfast?

Tenacity is rainfast one hour after the application has dried.

For best results, use with a non-ionic surfactant (NIS) and do not water (irrigation or rainfall) a minimum of six hours after applying Tenacity. The herbicide needs time to stick, dry, and penetrate the plant in order to eradicate the weed.

As mentioned, for pre-emergence, water in with 0.15 inches of water or rainfall after application. While the label says “within 10 days of application”, we suggest watering in the pre-emergent immediately.

And to summarize for improved postemergence weed control, use a NIS and do not water for at least six hours after applying Tenacity herbicide.

As a rule of thumb, never apply herbicides, including Tenacity, when the outside temperatures are 85 degrees Fahrenheit or over.

Rainproof for Preventative Contamination

The number one thing that a lawn care beginner can do is read the labels of all products. This section is equally as important as the others and can only be found when reading the label in its entirety.

“Poorly draining soils and soils with shallow water tables are more prone to produce runoff that contains this product.

Runoff of this product will be reduced by avoiding applications when rainfall is forecasted to occur within 48 hours. Sound erosion control practices will reduce this product’s contribution to surface water contamination.”

To summarize, do not apply Tenacity Herbicide within two days of a known heavy rainstorm. be mindful of irrigation within two days of application.

Tenacity Herbicide Application Rates

Tenacity Herbicide has a maximum annual rate of 16 oz. per acre. This equates to roughly 0.37 liquid ounces per 1,000 square feet.

Tenacity Herbicide Label


Can you use Tenacity before it rains?

Yes and no. You can use Tenacity before it rains when as long as it is being applied as a pre-emergent. For post-emergent weed control, apply Tenacity herbicide at least six hours before rainfall or irrigation.

Can Tenacity get wet?

Tenacity can get wet when applying as a pre-emergent at the time of seeding. However, as a weed killer, Tenacity should be applied to dry turf, and allowed to dry on the plant for at least six hours before getting wet.

How long does it take for Tenacity to dry?

There are many factors that can affect the timing – mostly depending on the climate and time of day. Tenacity will dry quicker on a warm sunny day, and longer on a cooler day in the shade. However, Tenacity should be dry in roughly 1-2 hours after application.

When should I apply Tenacity to my lawn?

You can apply Tenacity to your lawn in the spring and fall when seeding and overseeding. Tenacity can also be used as a post-emergent weed killer that will eradicate crabgrass, clover, bentgrass, and dozens of other weeds.

More questions? Check out our huge Tenacity herbicide FAQ guide.

Was the information on this page helpful?

Thanks for your feedback!
Author's Note: this piece has been updated for accuracy since its first publication on
Photo of author
Author: Mark Marino
My name is Mark Marino, and I am the founder, owner, and operator of Lawn Phix. With a passion for lawn care and turf nutrition for over a decade, I've dedicated countless hours to correcting soil and perfecting lawns. Today, my expertise, backed by formal courses at UMass Extension Pesticide Education, allows me to offer top-tier lawn care services and advice. I am a fully licensed and insured lawn care applicator in Massachusetts, specializing in comprehensive turf nutrition, weed control, and lawn pest control. My license number is AL-0053865. Contact me at [email protected] or +1 (508) 500-8402.

Leave a Comment