If you're seeing clumps of bright green grass with seed heads in your lawn during spring, especially where your turf should still be dormant, chances are you're dealing with Poa annua—also known as annual bluegrass.
And by the time you see it... it's already too late.
What is Poa Annua?
Poa annua is a cool-season grassy weed that blends in during winter and early spring, but quickly turns pale, thins out, and dies off as temperatures rise—leaving behind bare spots and a patchy lawn.
Why It’s Showing Up in Spring
Even though it appears in spring, those ugly weeds with seeds, Poa annua actually germinates in the fall. That means the best way to control it is with action before it sprouts, not after you see it.
What You Should Know:
- These seeds do NOT come from your grass seed. Poa annua seeds are already in your soil. They can lay dormant for years, waiting for the right conditions.
- Aeration and overseeding can bring seeds to the surface. That’s why some customers see more Poa annua the year after seeding.
The Right Strategy to Prevent Poa Annua
If you want to stop Poa annua next spring, you need to act in the fall.
Option 1: Not Seeding? Use a Pre-Emergent in Fall
- Apply a pre-emergent herbicide (like our 0-0-7 or 13-0-10 with pre-emergent) around early September.
- This creates a barrier that stops Poa annua seeds from sprouting.
Option 2: Seeding This Fall? Use Etho Instead
If you're aerating and overseeding this fall, you can’t use traditional pre-emergents (they’ll block your grass seed too). But you still have a great option:
- Apply Etho (a specialty herbicide safe for new seedings) around early November, once your grass has germinated and is mowed at least once.
- Apply again in early December, mixed with a surfactant for best results.
- Etho helps prevent Poa annua from germinating without harming your new grass.
Summary
| Situation | What to Do | When to Apply |
|---|---|---|
| Not seeding this fall | Apply fall pre-emergent | Early September |
| Seeding this fall | Apply Etho + surfactant - 2x | Nov & early Dec |