What is an effective pre-emergent herbicide for lawns?
Choosing the right pre-emergent requires knowing exact product names and strict application timing relative to when you seed. Without clear notes, homeowners miss their narrow seasonal windows and struggle to figure out whether to spray products like Tenacity before or after laying new seeds and soil.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1Applying Hi-Yield Weed & Grass Stopper with Dithiopyr despite warnings that it will be minimally effectiveDid this help you?
- 2Considering multiple applications of the pre-emergent productDid this help you?
- 3going with Scott's triple action built for seedlingDid this help you?
- 4setting up sprinkler systems ahead of seeding to test connectionsDid this help you?
- 5Searching online for conflicting application guidelinesDid this help you?
- 6Applying mesotrione at seeding timeDid this help you?
- 7Applying Scott's starter granular fertilizer with mesotrione at the same time as seeding.Did this help you?
- 8Watering heavily in hopes of diluting the chemical barrier and salvaging some germinationDid this help you?
- 9Abandoning the watering process and accepting the loss of the seedDid this help you?
- 10Using Fiesta as the primary legal alternativeDid this help you?
- 11Ordering restricted products from another provinceDid this help you?
- 12Traveling to the United States to purchase banned productsDid this help you?
- 13Sourcing illegal delivery servicesDid this help you?
- 14Waiting for cooler temperatures in mid-OctoberDid this help you?
- 15Checking turf grass type sensitivity before applicationDid this help you?
- 16Creating a seed sandwich in bare spotsDid this help you?
- 17Skipping the standard fall pre-emergent applicationDid this help you?
- 18Using a seed-safe pre-emergent product containing mesotrioneDid this help you?
- 19Switching to a specialized seeding formula during the year you want to overseedDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“im trying to get ahead of these weeds this winter. i didnt have time last year and I paid for it this year.”source ↗
“pre emergent - this is where I need advice. Before nuking the lawn, I had : crab, dallis and clover galore.”source ↗
“Given that the seeds live in the dirt below, should I apply Tenacity before i even put down the seed? Or spray it over the top of everything after I've laid down the seed & soil?”source ↗
“I put the prodiamine down, then realized I meant to use the Torocity.”source ↗
“So options - water it and waste more money on the water bill? Or just let it go?”source ↗
“Am I now screwed with being able to overseed the Rye since the pre emergent is already down?”source ↗
“Secondary question, if I were to use a regular system like Scott’s fertilizer and weed control every few months during the year, how would a person ever be able to overseed since there would always be a barrier of pre emergent within 2-3 months at any given time?”source ↗
“I had my calendar marked to put down pre-emergent last weekend but my notes didn't specify which pre-emergent.”source ↗
“What else should I be looking at as an effective pre-emergent?”source ↗
“Was just wondering because I see tenacity recommended here for pretty much every new lawn seeding post.”source ↗
“My question is if you nuke your lawn/weeds with glysophate 2-4 weeks prior and then you seed after, do you need to apply tenacity in this situation or is the glysophate that was put down weeks prior already preventing new weeds from sprouting?”source ↗
“When should you do Tenacity in relation to over seeding?”source ↗
“Prodiamine is going to heavily ruin germination success, like 90%+ probably.”source ↗
“We’re limited to what we can use on our lawns here so looking for the best weed control I can legally use.”source ↗
“Well if you’re looking for something you can legally use in Ontario, you’re stuck with Fiesta. If you want to use a more effective product, you’ll have to order something from another province or take a trip to the states.”source ↗
“That soil temp is way too high for pre-emergent on new sod, you'd cook the roots before the weeds even think about germinating.”source ↗
“I am wondering if I can apply Prodiamine 65 WDG 30 days after seedling (so in another 2 weeks) in order to have continuing pre-emergent coverage on POA Annual?”source ↗
“Online search results on this subject is mixed but I don't think I can re-apply Mesotrione to an area with newly geminated tall fescue neither. What's my best option here?”source ↗
Where this came up
People with this problem also raised
- 112How to get rid of creeping weeds without breaking roots
- 29Should I kill crabgrass in late summer or wait for spring?
- 48How do I figure out what kind of grass I have?
- 5Is it safe for pets to walk on treated grass?
- 5Will putting peat moss over grass seed bury it too deep?
- 2How to stop weeds between fences and sheds without chemicals