An unusually warm March has central Illinois lawns greening up ahead of schedule, trees budding out early, and homeowners asking the same question: is it time to put down pre-emergent for crabgrass, or is it already too late?
Here is what you need to know.
Soil Temperature Is What Matters
Crabgrass germinates when soil temperatures reach the mid-50s consistently over several days. Despite the warm air temperatures this winter, overnight lows in the 20s and 30s have kept soil temperatures in the 40s across most of central Illinois. That means crabgrass has not yet germinated, and pre-emergent applications are still timely and effective.
Where Crabgrass Gets a Head Start
Not all areas of your lawn warm at the same rate. Edges along concrete driveways and sidewalks absorb heat faster and will hit germination temperatures before the rest of the lawn. Thin or bare areas are also more vulnerable. A dense, healthy stand of turf is naturally the best defense against crabgrass and annual weeds. If your lawn is thin, those areas deserve extra attention this spring.
If You Plan to Overseed, Skip the Pre-Emergent
Pre-emergent herbicides work by preventing seeds from germinating. That includes your new grass seed. If overseeding is part of your spring plan, let your lawn care provider know before the first application goes down. A pre-emergent applied over fresh seed will prevent germination and set back your overseeding effort entirely.
Green View's Approach This Spring
Given the early season, Green View will begin first applications in early March on most lawns. Initial applications will include a pre-emergent combined with fertilizer to support early growth while blocking crabgrass germination. As soil temperatures climb, we will transition to a combination pre- and post-emergent program to catch both seeds that have not yet germinated and those that have recently broken dormancy.
The timing of that transition matters. Central Illinois soil temperatures can shift quickly in March and April, and staying ahead of germination is the difference between clean turf and a crabgrass problem you are trying to manage all summer.