When to Put Down Pre-Emergent in Virginia (Chesterfield Dates)

Crabgrass seed germinates once soil temperature holds 50-55 F for three to five consecutive days. In Chesterfield County that usually happens in the first ten days of March, sometimes late February after a warm winter. Pre-emergent has to be on the ground and watered in before that, so the working target is February 20 to March 10.

Why the calendar date is a guess and the soil temperature is not

Forsythia blooming is the old-timer's cue and it is not bad, but it runs a week early some years. The reliable number is soil temperature at a two-inch depth. Two free ways to get it: the Virginia Tech Turfgrass soil temperature map, or a $12 probe thermometer in the sunniest part of the lawn at 8 a.m. When you see 50 F three mornings in a row, the window is closing.

South-facing slopes in Salisbury and Hallsley warm first. Shaded Brandermill and Woodlake lawns run a week behind. Full-sun lawns in Chester and Ashton Woods are usually the first in the county to cross 55 F.

What to use on tall fescue

• Prodiamine (the active in most professional programs): one application at the full rate lasts roughly 4 months; a split application (March and again in late May) covers the whole crabgrass season.
• Dithiopyr gives you about three weeks of grace - it kills crabgrass that has just germinated - which makes it the better choice if you missed the window.
• Pendimethalin works but stains everything yellow and is shorter-lived.

Two rules that catch people out. First, pre-emergent stops all seed, including tall fescue seed, so do not seed a lawn in spring that you treated in March; this is one more reason fall seeding is the Virginia norm. Second, it has to be watered in with about a half inch of rain or irrigation within a few days or it sits on the surface and does nothing.

The second application

Crabgrass keeps germinating through June. A single March application at a light rate runs out in early summer, which is exactly when the lawn is under the most heat stress and least able to compete. Professional programs in Chesterfield put down a second round in mid to late May, often combined with the summer fertilizer. Ask whether the program you are quoted is one round or two; it changes the result more than the brand of product.

What if you missed it

If crabgrass is already up and green, pre-emergent will not touch it. Use a post-emergent with quinclorac while the plants are small (three tillers or fewer), keep mowing at 3.5-4 inches so the fescue shades the soil, and plan the fall aeration and overseed that thickens the lawn enough to crowd crabgrass out next year. A thick fescue lawn is the only pre-emergent that never expires.

What it costs in Chesterfield

Pre-emergent is round one of a six-application program. For a typical quarter-acre Chesterfield lot the program runs about $75-$100 per application; a third-acre Midlothian lot about $85-$115. Standalone pre-emergent visits are rare because the product is cheap and the trip is the cost. Virginia requires a VDACS commercial applicator certification for anyone applying it for pay, and every provider we match for fertilization has one on file.

Type your address to see the fertilization program range for your actual lot.