The Best Time to Apply Preemergent for Crabgrass
Crabgrass is one of the most notorious lawn invaders, especially in regions like Bakersfield, California, where the climate transitions swiftly from mild winters to warm springs. Once crabgrass gains a foothold, it can rapidly spread and crowd out your turfgrass, leading to an uneven, weedy appearance that’s difficult to manage. The good news is that preventing crabgrass is often far easier than trying to eradicate it after it emerges. In this article, we’ll explore why late winter to early spring is the best time to apply preemergent herbicide, how Bakersfield’s unique climate influences crabgrass growth, and the steps you can take to maintain a healthy, weed-resistant lawn year-round.
Understanding the Crabgrass Life Cycle
Before you can effectively prevent crabgrass, it’s helpful to know a bit about its life cycle. Crabgrass is an annual weed, which means it completes its entire life cycle in a single growing season. It thrives when soil temperatures reach 55°F–60°F, a range it can find relatively early in Bakersfield thanks to the region’s moderate winters and early spring warmth.
Seed Germination
Crabgrass seeds germinate in the early spring. Once the soil hits that critical temperature range, dormant seeds from the previous year begin to sprout.Rapid Growth in Warmer Temperatures
As spring turns into summer, young crabgrass plants grow aggressively. They spread horizontally, producing side shoots that can quickly overtake bare or thin spots in a lawn.Seed Production in Late Summer
By late summer or early fall, crabgrass plants produce seeds that drop to the soil, where they remain dormant through winter. The cycle then begins anew when spring returns.
The key to beating crabgrass is to interrupt this cycle before germination occurs. That’s where preemergent herbicides come in.
Why Preemergent Herbicides Are Essential
A preemergent herbicide is specifically designed to target weed seeds before they emerge from the soil. It forms a protective barrier that inhibits the growth of young seedlings, effectively blocking the emergence of crabgrass. However, timing is critical:
Preventing Germination
If you wait until after crabgrass has sprouted, a preemergent herbicide will no longer be effective against those seedlings. You’d have to switch to a post-emergent solution or resort to manual removal, both of which can be more labor-intensive and potentially harmful to your lawn if not done correctly.Early is Better
Because Bakersfield’s soil can warm up quickly, applying a preemergent too late may allow a substantial portion of crabgrass seeds to sprout first. Conversely, applying it too early might cause the herbicide’s active ingredients to break down before the peak germination period begins.
By carefully watching soil temperatures and weather patterns, you can strike the perfect balance—ideally applying your preemergent when soil temperatures start approaching the mid-50s for a sustained period.
Bakersfield’s Climate and Its Impact on Crabgrass
Bakersfield’s climate can be characterized by mild, wet winters and hot, dry summers, with spring temperatures often warming up faster than in many other areas of the country. This climate profile has two major implications for crabgrass control:
Earlier Germination Window
Because winters are relatively mild, and the transition to warmer spring temperatures is swift, the soil can reach that 55°F threshold as early as late February. Crabgrass seeds are essentially “on standby,” waiting for this moment to germinate.Prolonged Growing Season
The Central Valley’s extended period of warmth means that crabgrass can continue to thrive longer into the summer. In some cases, you may encounter multiple waves of germination, especially in lawns with bare spots or weakened turf. This is why some homeowners opt for split applications of preemergent: applying once in late winter/early spring and then again 8–10 weeks later to ensure continuous coverage.
Determining the Right Time to Apply Preemergent
Choosing the ideal moment to apply preemergent can feel like a guessing game, but there are a few practical ways to narrow it down:
Monitor Local Soil Temperatures
The most accurate method is to use a soil thermometer. Insert it a couple of inches into the ground (in an area of your lawn that receives direct sun) and check the readings daily. Once you notice consistent readings around 55°F–60°F, it’s time to act.Observe Weather Patterns
Keep an eye on daytime highs. If you’re seeing a stretch of days where highs reach 65°F–70°F, the soil is almost certainly approaching the germination-friendly zone.Watch for Early Blooms
Certain plants and trees begin to flower as soon as the soil and air temperatures rise—think of it as nature’s alarm clock. If you see signs of spring in your garden or your neighborhood, crabgrass seeds could be ready to sprout too.Stay Informed Locally
For region-specific advice, it’s always helpful to consult a trusted local resource. Here in Bakersfield, you can visit here for tips on what other homeowners are doing and what products work best in our climate.
Best Practices for Applying Preemergent
Once you’ve pinpointed the right timeframe, it’s important to apply your preemergent correctly to maximize its effectiveness:
1. Read the Label
Every preemergent herbicide has specific instructions regarding application rates, timing, and necessary precautions. Following these guidelines ensures that you use the product safely and effectively.2. Proper Calibration and Distribution
Whether you’re using a rotary or drop spreader, calibrate it to the settings recommended on the product label. Uneven application can create weak spots where crabgrass can sneak through.3. Water It In
Most preemergent formulations require water to activate the barrier in the top layer of soil. Lightly irrigate your lawn (or apply just before a gentle rain) so that the herbicide is washed into the root zone where seeds are likely to germinate.4. Avoid Disturbing the Soil
After applying preemergent, limit activities like raking, dethatching, or aerating for at least several weeks. Disrupting the soil can break the herbicide barrier and allow crabgrass to emerge.5. Consider a Split Application
Given Bakersfield’s extended warm season, you might benefit from a follow-up application 8–10 weeks after the first. This second dose helps maintain an effective barrier during the later waves of germination.
Ongoing Lawn Care for Long-Term Weed Prevention
While preemergent is a powerful tool, it shouldn’t be your only line of defense against crabgrass. Cultivating a healthy, vigorous lawn is the single most effective weed management strategy. Weeds flourish in stressed or thinning turf—when grass is weak, crabgrass seizes the opportunity to fill the gaps. Below are some foundational lawn-care tips to keep your turf in top shape:
Mow at the Proper Height
Each grass type has an ideal mowing height. For many warm-season grasses, keeping your lawn on the taller side helps shade the soil and discourage weed seedlings from taking hold.Water Smartly
Shallow, frequent watering encourages weak roots and can create an environment where weeds thrive. Instead, aim for deep and infrequent watering—once or twice a week—allowing moisture to reach the deeper root zone. This encourages stronger, deeper root systems and a more resilient lawn.Fertilize Appropriately
Over-fertilizing can lead to excessive top growth, while under-fertilizing can weaken your turf. Aim for balanced, slow-release fertilizers that deliver nutrients steadily over time, and follow recommended application schedules based on your specific grass type.Aeration and Dethatching
While you don’t want to aerate immediately after applying preemergent, performing these tasks periodically can help reduce soil compaction and remove thatch buildup, both of which can foster a healthier lawn. Just be mindful of timing—avoid doing this too close to your preemergent application date.Spot-Treat Problem Areas
Even the best-prepared lawns might see the occasional weed breakthrough. Hand-pulling or spot-treating isolated patches of crabgrass with a post-emergent herbicide can stop small problems from becoming widespread invasions.
Common Mistakes to Avoid
As you plan your preemergent strategy, steer clear of these common pitfalls:
Applying Too Late
Waiting until you see the first weeds often means the seeds have already germinated. Preemergent won’t work effectively on established seedlings.Skipping Watering
Forgetting to water in the herbicide or relying on heavy rain (which may not come when you need it) can result in an incomplete soil barrier.Inconsistent Coverage
If you leave gaps in coverage or apply unevenly, crabgrass will find those unprotected areas. Consistency is crucial for success.Neglecting Overall Lawn Health
A lawn that’s chronically under-watered, scalped by low mowing, or never fertilized is essentially an open invitation for crabgrass, regardless of how accurately you time your preemergent application.
Where to Find More Information
For those living in Bakersfield or other parts of the Central Valley, localized advice can make a big difference. Understanding your soil type, local weather patterns, and specific grass varieties can help you fine-tune your preemergent application schedule and lawn-care practices. We encourage you to visit here for weed control insights and product recommendations tailored to our region’s unique conditions.
Final Thoughts
Crabgrass is relentless, but it’s far from unbeatable—especially if you act proactively. By applying a preemergent herbicide in late winter or early spring, you’ll stop the weed at its most vulnerable stage: before it emerges. Combine this strategy with consistent watering, proper mowing, and balanced fertilization, and you’ll give your lawn the competitive edge it needs to outgrow crabgrass and other unwanted invaders.
Key Takeaways
Timing is everything: Aim for late winter to early spring, just as soil temperatures near the 55°F mark.
Prep for longevity: Consider a split application if Bakersfield’s extended warm season leads to multiple germination periods.
Think holistically: Healthy lawns are less susceptible to weeds, so focus on strong turf management.
Stay informed: Local resources like Grass Roots Bakersfield can guide you toward the right products and practices for your specific lawn needs.
By following these guidelines, you’ll be well on your way to a lush, green, crabgrass-free lawn—even under the challenging conditions of a Bakersfield summer. If crabgrass has been your recurring nightmare, rest assured that a well-timed, well-executed preemergent program can make all the difference. A little planning now ensures a more enjoyable, stress-free lawn season later.