Spring Seeding with Weed Protection (Mesotrione Bridge)
Spring seeding usually means choosing between new grass and weed control. The mesotrione bridge lets you have both — here's the protocol.
By Lawn Sense Team · Updated
The Spring Seeding Dilemma
If you seed your lawn in spring, you face a catch-22: the herbicides that prevent crabgrass (called pre-emergents) also prevent your new grass seed from growing. But if you skip the herbicide, crabgrass will overwhelm your seedlings. The mesotrione bridge protocol solves this by using a special herbicide (mesotrione, brand name Tenacity) that blocks weeds while letting grass seed grow normally.
How Mesotrione Works
Mesotrione (brand name Tenacity) is unique among pre-emergents because it is safe for use at the time of seeding on most cool-season grasses. It provides 28-30 days of pre-emergent crabgrass control while allowing your grass seed to germinate normally.
Important: Mesotrione can damage fine fescue. If your seed mix contains fine fescue, use caution and consider fall seeding instead.
The Three-Step Bridge
Step 1: Seed Day
- Aerate and seed
- Apply mesotrione at label rate
- Apply starter fertilizer (24-25-4)
- Begin seeding watering protocol
Step 2: Day 28-30
- If you have completed 2 mows: apply dithiopyr (Dimension) at half rate
- If fewer than 2 mows: apply second mesotrione application
Step 3: Day 60+
- Apply prodiamine at half rate for remainder of season
- Full herbicide restrictions lifted after 3 mows or 60 days
Post-Emergent Restrictions
During establishment, post-emergent herbicide use is restricted based on mow count:
- 0-1 mows: No herbicides. Hand-pull only.
- 2 mows: Mesotrione spot-treatment OK
- 3 mows or 60 days: All restrictions lifted
Recommended Products
Affiliate disclosure: we may earn from qualifying purchases.
Mesotrione 40%
Pre-emergent protection during new seeding or overseeding. Also post-emergent on select broadleaf and grassy weeds.
$30-70
Mesotrione (granular) + starter fertilizer
Beginners doing their first overseeding who want a simple one-product solution
$25-35
24-25-4 (high phosphorus starter fertilizer)
New seeding and overseeding — high phosphorus for root establishment
$20-30
Dithiopyr 24%
Split-app first pass, late starters, or anyone planning fall overseeding
~$160
Related Weeds
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