Iowa Lawn Care Calendar

How to Use This Calendar

This is a guide for the Iowa City corridor and Eastern Iowa generally. Timing shifts a week or two earlier or later based on weather each year. Pay attention to soil temperature and weather patterns, not just the calendar date.

March — Wake-Up Time

Early March

• Lawn is still dormant. Don't walk on it when frozen — you'll crush the crowns.
• Service your mower: sharpen blades, change oil, replace spark plug
• Plan your season — set seeding, fertilizing, and cleanup dates

Late March

• First raking of debris and leftover leaves (only if ground is dry)
• Watch soil temperatures — pre-emergent timing window is approaching

April — Spring Setup

Early to mid-April

• Apply pre-emergent herbicide for crabgrass — this is the most important spring task
• Complete spring cleanup (debris, light raking, garden bed work)
• Fix snow plow damage with patch seeding (skip pre-emergent in repair areas)

Late April

• First mow of the year — cut at 3 inches and stay tall
• First fertilizer application — slow-release nitrogen (24-0-6 or similar)

May — Active Growth

• Mow weekly at 3-3.5 inches
• Spot treat broadleaf weeds (dandelions, clover) on actively growing leaves
• Watch for crabgrass — pre-emergent should still be active
• Late May: Second fertilizer application before summer heat
• Bare spots? Last chance for spring overseeding before summer

June — Pre-Summer Prep

• Mow weekly at 3-3.5 inches
• Watch for grub damage and chinch bug damage
• Apply preventive grub control if needed (varies by property history)
• Raise mower height slightly as temperatures climb

July — Survive the Heat

• Raise mower deck to 3.5-4 inches — tall grass shades soil and conserves moisture
• Water deeply 1-2x per week (1 inch total) in early morning
• Skip fertilizer — feeding stressed grass in heat causes burn
• Watch for fungal diseases — brown patches, rings, or web-like growth
• Lawn may go dormant in extreme heat — that's normal, it'll come back

August — Recovery Begins

Early August

• Keep mowing tall (3.5-4 inches)
• Water deeply if no rain — dormant lawns can stay dormant but living roots need some moisture

Late August

• Heat breaks — lawn starts active growth again
• Plan fall aeration and overseeding for September
• Order seed in advance — supplies tighten as fall demand picks up

September — The Most Important Month

September is the single most important month for cool-season lawn care in Iowa.

• Core aerate — this is the prime window
• Overseed — within 48 hours of aerating
• Apply fall fertilizer — slow-release, this is the most important feeding of the year
• Water consistently for 2-3 weeks after seeding
• Drop mowing height back to 3-3.5 inches

October — Fall Maintenance

• Continue mowing weekly through October
• Start leaf removal as they drop — don't let them pile up
• Spot treat perennial broadleaf weeds (dandelions, ground ivy) — fall applications are extremely effective
• New seed should be established and ready for fertilizer if not already applied

November — Winter Prep

• Final leaf cleanup — get every last leaf off the lawn
• Final mow at 2.5 inches before dormancy
• Apply winterizer fertilizer (high potassium formula)
• Blow out irrigation system before first hard freeze
• Disconnect and drain garden hoses
• Drain and store mowers; sharpen blades for spring

December — January — February: Dormant Season

• Stay off the frozen lawn when possible
• Avoid piling snow from driveways onto the same lawn spots repeatedly — this causes snow mold
• Use ice melt carefully — it damages turf along driveways and walkways
• Plan next year: review what worked, what didn't, and what to change

Quick Reference — The Big Three

1. Mid-April: Pre-emergent herbicide for crabgrass
2. Early September: Aerate + overseed + fertilize
3. Mid-November: Final leaf cleanup + winterizer fertilizer

If you only do three things on your lawn each year, do those three. Everything else is optimization on top of these fundamentals.