When to Apply Pre-Emergent in Northern Virginia

As winter begins to fade and temperatures slowly rise, many homeowners across Northern Virginia start thinking about spring lawn care. One of the most important — and most commonly missed — steps happens before you see any weeds at all: applying pre-emergent.

If timed correctly, pre-emergent can make or break your lawn’s appearance for the entire season. Applied too early or too late, and its effectiveness drops significantly.

In this article, we’ll explain when to apply pre-emergent in Northern Virginia, how soil temperature plays a role, and what else you should be doing now to prepare your lawn for spring. 

Pre-emergent is a preventative lawn treatment designed to stop weeds like crabgrass before they ever break through the soil surface. Instead of killing existing weeds, it creates a protective barrier that prevents seeds from germinating. 

That’s why timing is everything

Apply it too early, and the product can break down before weeds begin to germinate. Apply it too late, and the weeds have already taken hold — making pre-emergent far less effective.

Many homeowners assume pre-emergent should be applied on a specific date, but in Northern Virginia, soil temperature matters far more than the calendar. 

The general rule: 

Crabgrass begins to germinate when soil temperatures consistently reach 53–55°F.

In our region — including areas like Manassas, Gainesville, Fairfax, and Tysons — this typically occurs between late February and early April, depending on weather patterns. 

Warm spells in late winter can trick lawns into waking up early, which is why professional monitoring is key. 

Applying pre-emergent too early is a common mistake. 

When applied prematurely: 

• The product can degrade before weed germination begins 
• Protection may wear off before peak crabgrass season 
• A second application may be required later 

Professional timing ensures maximum coverage during the critical germination window.

Pre-emergent works best when paired with proper early-season preparation. Here’s what homeowners should focus on before mowing season begins: 

✔ Clean Up Winter Debris 

Remove leaves, sticks, and debris that block sunlight and trap moisture. 

✔ Address Drainage Issues

Soggy areas can delay soil warming and promote weed growth. Persistent wet spots should be evaluated early. 

✔ Avoid Heavy Disturbance After Application 

Aggressive raking or aeration after pre-emergent can break the protective barrier. 

✔ Inspect Turf Health

Thin or stressed turf allows weeds to establish more easily once temperatures rise. 

✔ Plan Your Spring Lawn Program 

Pre-emergent is just one part of a successful season. Fertilization, mowing height, and proper watering all play a role. 

While pre-emergent products are available to homeowners, proper timing, coverage, and application rate determine whether it actually works.

A professional lawn program ensures:

• Soil temperature monitoring
• Correct product selection
• Even application
• Integration with fertilization and turf health plans

This approach delivers stronger results and reduces the need for corrective treatments later in the season.

At GreenWish, we help homeowners and commercial property owners throughout Northern Virginia prepare their lawns for a successful growing season.

Our early spring services include:

• Pre-emergent applications
• Lawn evaluations
• Drainage and turf health assessments
• Ongoing maintenance programs

Taking action now can prevent weed problems, reduce long-term costs, and set your lawn up for a healthy, green season.