Trimec can be applied any time weeds are visible in your yard and temperatures are 65–85℉ (18–29℃). Apply Trimec at least 24 hours before rain or lawn watering. This allows time for the herbicide to dry and fully infiltrate the plant system. Trimec is a powerful herbicide that should be used no more than 2 times per year, with at least 30 days between applications. This application schedule will wipe out weeds without harming grass.
What is Trimec?
The original Trimec formula (sold as Trimec Classic or Trimec Lawn Weed Killer) is a weed killer spray that combines 2,4-D with Mecoprop and Dicamba. These three ingredients attack broadleaf weeds, such as dandelion and white clover without harming grass. Because it is a post-emergent herbicide, Trimec kills weeds that have sprouted but does not linger in the soil to stop seeds from sprouting.
- Trimec is a selective weed killer that does not harm grass.
- As a post-emergent weed killer, Trimec only kills visible weeds. It won’t stop weed seeds from sprouting.
- Trimec Lawn Weed Killer is designed for broadleaf weed control.
- Trimec Crabgrass contains Quinclorac, an added ingredient that kills crabgrass along with broadleaf weeds.
Trimec variants designed to kill crabgrass contain Quinclorac. This ingredient attacks crabgrass without harming most turf grass species. Avoid Quinclorac products if your lawn is St. Augustine or Centipede grass. This product will harm those two grass species. Quinclorac is safe for all other grass types at standard application rates. For St. Augustine and Centipede grass lawns, spray an Atrazine-based weed killer to wipe out crabgrass without harming your turf.
At What Temperature Should You Spray Trimec?
Temperatures between 65 and 85 degrees Fahrenheit (18–29℃) are the best for Trimec application. If temperatures are above 85 degrees, the weed killer may evaporate before it is absorbed. Plus, plants may develop waxy leaf cuticles in hot weather that resist herbicide.
- Apply Trimec when temperatures are 65–85℉ (18–29℃).
- Hot temperatures increase the chance of weed killer evaporating before it infiltrates the plant.
- Trimec applied in cold weather is less effective because plants absorb the herbicide less effectively.
In cold weather, a plant’s metabolism slows. Because the chemicals in Trimec must be transported through the plant’s leaves, an application in cold weather is slow to work. In cold conditions, the herbicide may be introduced to the plant at such a slow trickle that it won’t kill the weed.
How Long Should Trimec Be Applied Before Rain?
Spray Trimec at least 24 hours before you expect any rain. This gives the weed killer time to work. Rain or water from a sprinkler system can dilute the Trimec or wash it off the plant’s leaves, rendering it useless.
- Trimec is best applied at least 24 hours before rain.
- Water from precipitation or sprinkler system will wash Trimec off plant leaves.
- Trimec is best applied on a wind-free day. This prevents overspray and rapid evaporation.
For best results, apply Trimec in dry, windless conditions. Wind can carry droplets of Trimec onto plants you never intended to spray, damaging them. Additionally, wind increases the rate at which liquids evaporate. Trimec applied in windy conditions may evaporate before it can do its work.
How Often Can You Use Trimec?
You can spray Trimec in a single area up to 2 times per year. However, Trimec applications should be at least 30 days apart. An overload of Trimec in one area can damage the turf grass you wish to protect. Follow manufacturer instructions for sprayer application rates to avoid using too much Trimec at once.
- Trimec can be applied twice per year.
- Apply Trimec no more than once in a 30-day period.
- Trimec often shows initial weed killing results in 24 hours, with full weed death in 7–10 days.
Trimec acts fast. With its 3-herbicide blend, it can cause weeds to start wilting within 24 hours of application. Keep in mind, Trimec is a systemic herbicide and needs time to kill weeds down to the root. Wait at least 7 days after the application for Trimec to fully kill weeds.
What Weeds Does Trimec Control?
Standard Trimec, sold as Trimec Lawn Weed Killer, is a grass-safe broadleaf weed killer. It won’t wipe out your crabgrass but it will kill non-grassy weeds. Whether it’s thistles, plantains, or dandelions, Trimec can wipe it out.
- Trimec Lawn Weed Killer kills broadleaf weeds such as dandelions, clover, chickweed, and purslane.
- Trimec Lawn Weed Killer will not kill pest grasses or desirable grass.
- Trimec Plus Crabgrass Killer kills broadleaf weeds and crabgrass.
- Trimec products with crabgrass killer are still safe for all desirable grass types except St. Augustine and Centipede grass.
If you want to kill crabgrass and broadleaf weeds at the same time, look for a Trimec product that advertises crabgrass-killing power on the label. These formulations will wipe out all the same broadleaf weeds as traditional Trimec, with the added bonus that they kill crabgrass too. All this is accomplished without harming the grass in your yard.\
When Should You Spray Trimec?
When considering Trimec application, keep the following rules in mind:
- Apply when temperatures are 65–85℉ (18–29℃)
- Spray at least 24 hours before any expected rain.
- Use Trimec no more than 2 times per year in the same area.
- Allow at least 30 days between Trimec applications in the same area.
- If you are using a Trimec product with Crabgrass control, do not spray it on St. Augustine or Centipede grass lawns.
These quick guidelines will help you get the most out of your Trimec weed killer. Remember to follow product label warnings and application rates to keep yourself and your yard safe.
