March Madness: Taking Down Weeds Before They Take Over Your Lawn

March in Southern California isn’t just about busted brackets and buzzer-beaters. It’s also the start of something far less fun — weed season.

While you’re filling out your bracket, weeds are quietly drafting themselves into your lawn. But don’t worry — this is the month to shut them down before they become championship contenders.

Let’s break down your weed control game plan.

Why March Is Prime Time for Weed Control

In March, soil temperatures start rising across Southern California. That’s the signal for summer weeds like crabgrass to begin germinating.

You might already be seeing:

• Dandelions
• Clover
• Spurge
• Early crabgrass

If your lawn is thin or stressed, weeds see that as open court space.

A thick, healthy lawn? That’s a full-court press.

The Best Defense: A Dense Lawn

Cool-season grasses like Marathon (a tall fescue variety popular here in SoCal) are naturally competitive when properly maintained.

Why tall fescue works well:

• Deep root system
• Good wear tolerance
• Stays green with proper irrigation
• Crowds out weeds when maintained at proper height

But here’s the key — mowing height matters.

Keep tall fescue around 3 inches. Taller grass shades the soil, reducing weed germination. Scalp it low, and you’re basically inviting weeds onto the court.

Not All Herbicides Are the Same – Adjust Your Gameplay Based on Your Opponent

Pre-Emergent: Stop Weeds Before They Sprout

March is often the last window to apply pre-emergent before soil temps consistently warm up.

Pre-emergent:

• Prevents weed seeds from sprouting
• Does NOT kill existing weeds
• Works best when applied before germination

Important:

If you recently installed new sod, hold off on pre-emergent until the lawn is well established. New roots need time to develop.

If you’re unsure whether it’s safe for your lawn, it’s better to wait than risk stressing young grass.

Post-Emergent: Overtime Strategy

Already seeing weeds? You’ll need a post-emergent herbicide designed for your grass type.

For tall fescue lawns:

• Spot treat instead of blanket spraying
• Apply on non-windy days
• Follow label instructions carefully

Herbicides work best on actively growing weeds. March is ideal because weeds are young and vulnerable.

Learn more about weeds

Watering: Don’t Help the Enemy

Overwatering in March is one of the biggest mistakes seen in Southern California.

Too much water:

• Encourages shallow roots
• Promotes fungal issues
• Creates ideal weed conditions

Use the ET Irrigation Calculator on sod.com to determine proper watering for your specific city and grass type.

Deep, infrequent watering (once established) strengthens turf and makes it harder for weeds to compete.

Fertilize Smart, Not Aggressive

A light, balanced feeding in early spring can help your lawn thicken up — and thickness is your best weed prevention tool.

Avoid heavy nitrogen blasts. Over-fertilizing can:

• Cause excessive top growth
• Increase mowing frequency
• Stress roots

Slow and steady wins this tournament.

Cultural Practices = Long-Term Victory

Weed control isn’t just about products. It’s about habits:

• Mow high
• Water deeply but less often
• Overseed thin spots (in fall)
• Improve soil health
• Reduce compaction

Healthy turf doesn’t leave space on the roster for weeds.

The Final Buzzer

March is when the weed battle is won or lost in Southern California.

If you:

• Strengthen your turf
• Apply pre-emergent at the right time
• Spot treat early weeds
• Water wisely

You’ll head into summer with a lawn that looks like a #1 seed.

No luck required. Just good timing and smart lawn care.