February in the Southeast is deceptive. The air still has a chill, your Bermuda or Zoysia is brown and dormant, and it feels like spring is weeks away. But underground, weed seeds are already sensing soil temperatures — and once those temps hit 55°F for several consecutive days, crabgrass and goosegrass start germinating.

That’s why pre-emergent timing is the single most important decision you’ll make for your Southeast lawn this month.

Why Timing Matters More Than Product

Here’s the thing most homeowners get wrong: they obsess over which pre-emergent to buy but apply it two weeks too late. A perfectly chosen product applied after germination does almost nothing. A decent product applied at the right time does everything.

Pre-emergent herbicides work by creating a chemical barrier in the top inch of soil. Weed seedlings hit that barrier and die before they ever break the surface. But if seeds have already sprouted and pushed roots below that barrier? You’ve missed your window.

When to Apply in the Southeast

The general rule is to apply when soil temperatures reach 55°F at a 4-inch depth for 3-5 consecutive days. In practice, here’s what that looks like across the region:

  • North Florida and Gulf Coast: Late January to mid-February (you may already be close — check your soil temps now)
  • Georgia, Alabama, Mississippi, South Carolina lowcountry: Mid-February to early March
  • North Carolina Piedmont, Tennessee, northern Georgia: Late February to mid-March
  • Mountain areas of NC, TN, and north Alabama: Early to mid-March

If you don’t own a soil thermometer, they’re under $15 and worth every penny. Stick it in a shady spot in your lawn at 4 inches deep. Check it at the same time each morning for a week.

Pro tip: A reliable old-school indicator is when forsythia bushes bloom and dogwoods start budding. Nature’s been doing this longer than we have.

Choosing the Right Pre-Emergent

For Southeast warm-season lawns (Bermuda, Zoysia, St. Augustine, Centipede), these active ingredients work well:

  • Prodiamine — Long-lasting, excellent crabgrass control, budget-friendly in granular form. This is the go-to for most homeowners.
  • Dithiopyr (Dimension) — Offers a short window of early post-emergent activity, meaning it can still work on very young crabgrass seedlings. Great if you’re worried about timing.
  • Pendimethalin — Widely available (it’s what’s in most big-box pre-emergent products). Effective but shorter residual than prodiamine.

Avoid pre-emergents containing atrazine on Bermuda or Zoysia — it’s only safe for St. Augustine and Centipede lawns.

Application Tips That Actually Matter

  1. Water it in within 24-48 hours. Pre-emergent needs to reach the soil to form that barrier. If it sits on top of grass blades, you’re wasting money. A half-inch of irrigation or rain activates it.

  2. Don’t aerate after applying. Core aeration punches holes right through your chemical barrier. If you need to aerate, do it before your pre-emergent application.

  3. Use a split application for longer control. Instead of one heavy dose, apply half your rate now and the other half 6-8 weeks later. This extends protection through late spring when a second wave of weeds tries to germinate.

  4. Calibrate your spreader. Too little = gaps in coverage. Too much = potential damage to your lawn or wasted product. Most bags have spreader settings listed — use them.

  5. Don’t skip edges and transitions. Weeds love the seams — along driveways, sidewalks, flower beds, and where your lawn meets your neighbor’s. Hit these areas deliberately.

What If You’re Planning to Overseed?

If you overseeded with ryegrass last fall and it’s still growing, pre-emergent won’t hurt your existing ryegrass — it only prevents new germination. However, if you’re planning to seed Bermuda or any warm-season grass this spring, do not apply pre-emergent in those areas. It’ll prevent your desirable grass seed from germinating too.

In that case, plan to manage weeds manually or with targeted post-emergent sprays after your new grass establishes.

The February Checklist for Southeast Lawns

Beyond pre-emergent, here’s what you should be doing right now:

  • Sharpen your mower blades. Your first mow is 4-6 weeks away. Be ready.
  • Soil test if you haven’t in 2+ years. Your county extension office usually offers free or cheap testing. Knowing your pH and nutrient levels before you fertilize saves money and gets better results.
  • Clean up debris. Leaves, sticks, and matted grass block sunlight and trap moisture, inviting fungal disease as things warm up.
  • Plan your fertilization schedule. Your first feeding should come after your lawn greens up and you’ve mowed it 2-3 times — not before. Fertilizing dormant warm-season grass is throwing money on the ground.

For more on getting warm-season grasses through seasonal transitions, check out our post on implementing effective winter lawn care in the Southeast. And if you’re dealing with specific weed identification challenges, our guide on preparing your Southeast lawn for spring covers the full transition playbook.

The Bottom Line

Pre-emergent is your lawn’s insurance policy. It costs a fraction of what you’d spend fighting established weeds all summer, and it takes about 30 minutes to apply. Get your soil thermometer out this week, watch those temperatures, and be ready to put down your first application the moment conditions are right.

Your Southeast lawn is about to wake up. Make sure the weeds don’t beat it to the punch.

Want the complete region-specific playbook for your Southeast lawn? Our Lush Lawns: Southeast edition covers fertilization schedules, mowing heights, pest management, and seasonal care tailored to your warm-season grass — month by month.