When To Apply Dimension Pre-Emergent

When to Apply Dimension Pre-Emergent

If you've ever battled crabgrass, you know the pain of seeing it spread like wildfire. But there's good news: you can beat it before it even sprouts.

This guide on when to apply Dimension pre-emergent will help you strike at the perfect moment using professional-grade products enhanced for homeowners.

At Lawn Synergy, we believe in empowering you with pro-level tools and expert support to help you get that lawn just right. Ready to block weeds before they start? Let's dig in.

What this article covers:

What Is Dimension Pre-Emergent?

Dimension is a professional-grade, selective pre-emergent herbicide powered by the active ingredient Dithiopyr.

What sets it apart is its dual-action capability: it not only prevents weed seeds from germinating, but it also controls newly sprouted weeds (especially crabgrass) up to the five-leaf stage, which gives you a wider window of effectiveness than traditional pre-emergents.

Why Homeowners Love It (and Pros Trust It)

Dimension isn't some generic product sitting on the shelf at your local big-box store.

It's a go-to for turf managers on high-end estate properties, golf courses, and sports turf, and Lawn Synergy has made it accessible, convenient, and optimized for DIY homeowners.

Here's why it's your not-so-secret weapon:

  • Dual-Action Control: Most pre-emergents only stop seeds from sprouting. Dimension goes a step further by controlling early-stage weeds, meaning you get effective protection even if you miss that narrow pre-germination window.
  • Extended Application Window: Thanks to Dithiopyr's early post-emergent control capabilities, Dimension gives you more flexibility. It's forgiving if you're a bit late — but still effective when timed right.
  • Turf-Safe and Versatile: Whether your lawn is Bermuda, Zoysia, Fescue, or Kentucky Bluegrass, Dimension is safe for use on most established turf types and won't harm your lawn when applied correctly.
  • Proven Performance: These are not test-tube formulations. They've been used for decades on luxury landscapes and sports turf, and we've enhanced them with added nutrients and customized packaging to make them perfect for homeowner-scale application.
When To Apply Dimension Pre-Emergent

Popular Homeowner-Friendly Dimension Fertilizer

These professional-grade, nutrient-rich, and precision-engineered to help homeowners like you succeed: 

At Lawn Synergy, we’ve taken the complexity out of high-end turf care and packaged it with support and guidance you won’t find anywhere else. You bring the effort — we bring the expertise.

The Best Time to Apply: Timing by Soil Temperature

Success with Dimension doesn't come from marking your calendar — it comes from reading your soil. And that's where most DIY lawn enthusiasts go wrong.

You need to understand the ideal soil temp for pre-emergent to get the full protective power of Dimension.

Weed seeds are triggered by warmth, not dates. So forget the “March means go” myth. Let your soil temperature guide your timing.

Spring Application: Block Crabgrass Before It Breaks Through

When to apply: When soil temperatures consistently hit 50°F to 55°F at a 2" depth for 3–5 days.

This temperature range is when crabgrass, your lawn's #1 enemy, begins germinating. The goal is to apply Dimension just before this germination window opens.

Doing so lays down a protective herbicide layer in the soil, stopping weeds before they can even start — it's like locking the door before the intruders show up. Want to get precise? Use a digital soil thermometer.

Pro Tip: Southern lawns warm up earlier. If you're in Florida or coastal Georgia, you may hit this temperature in late February or early March. North Carolina? Think late March into April.

When To Apply Dimension Pre-Emergent

Fall Application: Shut Down Winter Weeds Before They Settle In

When to apply: When soil temperatures drop below 70°F and continue trending downward.

Fall is your time to stop winter annuals like Poa annua (annual bluegrass), chickweed, and henbit. These weeds germinate when the weather cools down, then lie in wait to ruin your spring lawn.

By applying Dimension in early fall, you break the cycle — you control these nuisances before they can overwinter and explode in spring.

Fall Pre-Emergent Bonus: You get cleaner turf in the spring without the need for early spraying. That's especially helpful if you're prepping for a spring overseed or reseed (just remember, wait the appropriate time after Dimension before seeding!).

Application Guidelines for Dimension

You've got your timing down. Now it's about applying it right.

Whether you choose liquid, granular pre-emergent, or combo fertilizer forms, the key is coverage and activation.

Application Rates

  • Granular: Follow the rate listed on the label. Depending on formulation strength, it typically ranges from4 to 5 pounds per 1,000 sq. ft.

Watering In: It's Not Optional — It's Critical

Dimension must be activated by water to form that all-important barrier in the soil.

Here's how:

  • Apply 0.5 inches of water within 7 days of application.
  • This can come from irrigation or light rain.

Pre-emergent before rain? Absolutely.

Applying just before a modest rain is a perfect strategy. It saves you a watering cycle and ensures activation. Just be cautious of heavy storms that can cause runoff.

If you're using a fertilizer-infused product, this watering step also helps start the nutrient uptake process, giving your lawn a nice boost of green while the Dimension does its protective work below.

When To Apply Dimension Pre-Emergent

Best Practices for a Perfect Application

Applying Dimension and doing it right comes down to smart timing, lawn readiness, and strategic planning.

Here's how to ensure maximum effectiveness and protect the investment you're making in your lawn:

1. Avoid Overseeding Conflicts

Dimension (Dithiopyr) creates a chemical barrier in the soil that prevents seed germination. This is effective for controlling weeds, but it also affects desirable grass seed. Applying Dimension too close to seeding can result in poor or failed germination of turfgrass.

  • Before Seeding: If Dimension has been applied, wait a minimum of 6 to 8 weeks before overseeding or reseeding. This allows the pre-emergent barrier to break down enough to permit seed germination.
  • After Seeding: If you've recently overseeded, wait until the new grass has fully germinated, rooted, and been mowed at least twice. This ensures the turf is established enough to withstand herbicide application without damage.
  • Cool Season Grasses (like fescue, bluegrass): Fall seeding is common, so avoid fall pre-emergent applications unless seeding is not planned.  Only apply pre-emergent in early spring unless you are not fall overseeding.
  • Warm Season Grasses (like Bermuda, Zoysia): Avoid overseeding since these lawn types spread on their own.

2. Apply Only to Healthy Lawns

Dimension is designed for use on established, healthy turfgrass. Applying it to stressed or weakened lawns can lead to further damage and reduced herbicide efficacy.

Do Not Apply If Your Lawn Is:

  • Suffering from drought: Lack of moisture reduces herbicide movement in the soil and can damage already-stressed grass.
  • Under disease pressure: Lawns infected with fungal or bacterial diseases should be treated and recovered before applying any herbicide.
  • Experiencing extreme temperatures: Avoid applications during periods of high heat (above 85°F for cool-season grasses) or cold stress (below 50°F soil temps for warm-season grasses), as both can impair turf resilience.
When To Apply Dimension Pre-Emergent

3. Reapply for Long-Term Control

If you're in a region where weeds germinate in waves (like the Southeast), or you want season-long protection, a second application is smart.

  • Reapply Dimension 5 to 10 weeks after the first round.
  • This extends the barrier, especially helpful during long, warm springs or mild falls.

Our lawn care subscription program makes this super easy: you'll get the right product, at the right time, with support on exactly how and when to apply.

Conclusion

Mastering when to apply Dimension pre-emergent is one of the smartest steps you can take toward achieving a lawn that looks like it was maintained by a pro. Because, in partnership with Lawn Synergy, it is.

By timing your application to soil temperature and using professional-grade products enhanced with extra nutrients, you're setting yourself up for lush, thick, weed-free turf.

And you're never doing it alone.

At Lawn Synergy, we've taken estate-level lawn care, added extra performance, and sized it perfectly for the DIY homeowner. Plus, we back it up with real support, from soil testing to mixing tips and application guidance.

Let's get your lawn perfect — together

If you want to learn more, check out these articles below:

Back to Lawn Guide

Featured Product

LESCO 19-0-6 Dimension Pre-Emergent Fertilizer

LESCO 19-0-6 Dimension Pre-Emergent Fertilizer

$84.99