Monthly Lawn Care Schedule: What to Do Every Month in the PNW
You know lawn care is seasonal. But when exactly do you aerate? When does overseeding happen? When should you stop fertilizing?
Most homeowners guess. Then they wonder why their lawn doesn't improve.
Timing is everything in the Pacific Northwest. Do the wrong task in the wrong month, and you waste money and effort.
This is your month-by-month guide to exactly what your lawn needs—and when.
January: Rest & Plan
What to Do
Mowing: Stop mowing (grass dormant)
Fertilizing: Do NOT fertilize (grass not growing)
Overseeding: No
Aeration: No
Weed control: Not needed (cool, dormant season)
Pruning: Prune trees/shrubs for lawn health (improves light)
Planning: Assess lawn health; plan spring improvements
What to Avoid
- Don't apply fertilizer (wasted; won't be used)
- Don't try to seed (soil too cold)
- Don't aerate (dormant grass; no benefit)
- Don't walk heavily on frozen/wet grass (causes damage)
Weather Reality
- Wet, cold, short daylight
- Grass dormant; brown appearance is normal
- Rain common (PNW typical)
Your Task
Review: Walk your lawn and identify problem areas
- Thin spots
- Weed patches
- Drainage issues
- Shade issues
Plan: Note what to address in spring
February: Light Prep & Planning
What to Do
Mowing: Still dormant; don't mow
Fertilizing: No
Overseeding: No (too early)
Aeration: No
Weed control: No
Equipment prep: Sharpen mower blade; service equipment for spring
Tree work: Continue pruning if weather allows
Soil testing: Optional but good time (send to extension office)
What to Avoid
- Don't plant anything (frost risk until April)
- Don't fertilize (dormant grass)
- Don't overseed (won't germinate)
- Don't aerate (dormant turf)
Weather Reality
- Still cold; some late frost possible
- Slightly longer days than January
- Occasional freezing rain
Your Task
Prep for spring: Make sure equipment is ready
- Mower: Sharpen blade, change oil
- Spreader: Clean, test
- Trimmer: Check string, fuel
March: Spring Greening Begins
What to Do
Mowing: Start mowing as growth begins (late March only if needed)
- Don't mow until grass is 3+ inches
- Mow high (3–3.5 inches) initially
Fertilizing: Light spring application (late March)
- Use balanced fertilizer (10-10-10)
- Don't use heavy nitrogen (promotes weak growth)
Overseeding: Not yet (too early)
Aeration: Begin late March (soil warming)
- Only if soil is not saturated
- Wait for dry conditions
Weed control: Early spring pre-emergent available but not critical
Mulching: Refresh mulch in beds (prevent grass encroachment)
What to Avoid
- Don't mow too short (keep 3+ inches)
- Don't fertilize heavily (causes weak spring growth)
- Don't aerate in wet conditions (damages soil)
- Don't plant warm-season seed (too early)
Weather Reality
- Warming trend begins
- Rain still common
- Frost risk until mid-April
Your Task
Start growing season: Light mow, light fertilizer, prepare for heavy overseeding in fall
April: Growth & Preparation
What to Do
Mowing: Begin regular mowing schedule
- Weekly or bi-weekly depending on growth
- Maintain 2.5–3 inches height
Fertilizing: One more light application
- Mid-April only
- Balanced fertilizer again
Overseeding: Not yet (wait for fall)
Aeration: Complete spring aeration (early April ideal)
- Most important aeration of year
- Breaks winter compaction
- Cost: $75–200
Weed control: Spot-treat emerging weeds
- Pre-emergent applied (pre-emergence window closing)
Yard cleanup: Remove debris from winter
What to Avoid
- Don't fertilize heavily (causes weak growth)
- Don't skip aeration (most critical month)
- Don't overseed (won't thrive; wait for fall)
- Don't use heavy herbicide (young grass vulnerable)
Weather Reality
- Warming significantly
- Growth accelerating
- Rain decreasing (slowly)
Your Task
Aerate (critical): Schedule professional aeration or rent equipment
- Most important lawn task of spring
- Breaks compaction; enables root growth
- Breaks down thatch
May: Growth Season in Full
What to Do
Mowing: Regular weekly mowing
- 2–2.5 inches height (slightly shorter now that temps rising)
- Increase frequency if growth rapid
Fertilizing: STOP fertilizing until fall
- No spring fertilizer after May
- Wait for fall heavy fertilization
Overseeding: Not yet (hold for fall)
Aeration: Complete (if not done in April)
- Last window for spring aeration
Weed control: Ongoing spot treatment
- Hand-pull dandelions before seed
- Spot-spray emerging broadleaf weeds
Irrigation: Begin watering if dry
- Monitor soil moisture
- Water deeply 1–2x per week if no rain
What to Avoid
- Don't fertilize (saves money; won't help)
- Don't overseed (heat coming; wrong timing)
- Don't water if rain adequate (waste)
- Don't neglect mowing (grows fast now)
Weather Reality
- Warm, sunny days becoming common
- Rain decreasing
- Growth peak (nutrients peak)
Your Task
Establish rhythm: Regular mowing + watering = healthy lawn through summer
June: Summer Maintenance Begins
What to Do
Mowing: Weekly mowing
- Maintain 2.5–3 inches (slightly taller than May helps drought tolerance)
- Don't bag clippings (return to lawn; nutrients)
Fertilizing: None (hold until fall)
Overseeding: None
Aeration: None (dormancy approaching; too hot)
Weed control: Spot-treat only
- Most weeds also struggling in heat
- Focus on summer annuals
Irrigation: Increase to 2–3x per week if dry
- 1–1.5 inches water per watering
- Early morning best
Moss treatment: If moss visible, spot-treat (optional)
What to Avoid
- Don't fertilize (causes summer stress)
- Don't mow short (stresses in heat)
- Don't overseed (too hot; will fail)
- Don't let lawn dry completely (water schedule)
Weather Reality
- Warm, dry (PNW summer pattern)
- Grass slowing growth
- Days longest of year
Your Task
Maintain, don't improve: Focus on consistent watering + mowing
July: Hot & Dry Season
What to Do
Mowing: Reduce frequency if dry
- May shift to bi-weekly if soil dry
- Don't scalp; keep 3+ inches
Fertilizing: None
Overseeding: None
Aeration: None
Weed control: Minimal (weeds also struggling)
Irrigation: 2–3x per week
- Deep watering (1.5 inches)
- Early morning only
- Focus on problem areas
Shade: Prune trees to improve light (helps drought tolerance)
What to Avoid
- Don't fertilize (stresses grass in heat)
- Don't overseed (guaranteed failure in heat)
- Don't mow short (heat stress)
- Don't waste water on established lawns (PNW summer doesn't last long)
Weather Reality
- Hottest, driest month of year
- Low humidity (unusual for PNW)
- Grass slowed; may yellow slightly (normal)
Your Task
Survive heat: Water consistently; don't stress with mowing
August: Transition & Preparation
What to Do
Mowing: Return to weekly
- Growth resuming as temps cool
- Maintain 2.5–3 inches
Fertilizing: None yet (wait one month)
Overseeding: PREPARATION MONTH
- Don't seed yet, but prepare
- Scout for thin areas; mark them
- Aeration planned for September
Aeration: Not yet (wait for September)
Irrigation: Begin reducing (fall rains starting)
Yard prep: Clear debris; prepare for overseeding
What to Avoid
- Don't fertilize (wait for September heavy application)
- Don't overseed yet (wait for proper window)
- Don't water heavily if rain starting (conserve)
Weather Reality
- Hot but cooling trend
- First rain of late summer possible
- Growth resuming
Your Task
Prepare for fall overseeding: This is the most important season
September: CRITICAL OVERSEEDING MONTH
What to Do
Mowing: Continue weekly (Aug 15–Sept 15, then ease back)
Aeration: HEAVY AERATION (early September)
- Most critical aeration of year
- Breaks compaction; enables overseeding success
- Cost: $75–200
Overseeding: HEAVY OVERSEEDING (Sept 15–Oct 1 window)
- 5–8 lbs per 1,000 sq ft (heavy rate)
- Use quality seed (fine fescue + ryegrass blend)
- After aeration but before heavy fertilizer
Fertilizing: HOLD until seed established (week 3)
Irrigation: Begin heavy watering for seed
- 2–3x daily for 2 weeks post-seed
- Keep top 1 inch moist
- Critical for germination
Weed control: None (seed is priority)
What to Avoid
- Don't overseed before aerating (poor establishment)
- Don't overseed before Sept 15 (soil too warm)
- Don't underseed (light rate = poor results)
- Don't forget watering (seed will die)
Weather Reality
- Perfect temps for germination (60–70°F)
- Rain increasing
- Ideal conditions for seeding
Your Task
OVERSEEDING: This single month determines next year's lawn quality. Don't rush it.
Sequence:
- Aerate (early Sept)
- Wait 1 week for holes to open
- Overseed heavy (Sept 15–Oct 1)
- Water 2–3x daily (critical)
- By week 4, germinated and growing
October: Seed Establishment & Fertilization
What to Do
Mowing: Ease back; let overseeded grass grow
Overseeding: Complete by Oct 1
- Mow only if absolutely necessary
- Don't mow seeded areas
Fertilizing: HEAVY FALL FERTILIZATION
- High-nitrogen fertilizer (24-4-8)
- Apply late October (after seed established)
- Most important fertilization of year
- Cost: $50–150
Irrigation: Heavy watering continues 2–3 weeks post-seed
- Then transition to normal (less frequent)
Aeration: Complete for year
Weed control: None (don't stress new seed)
What to Avoid
- Don't fertilize before seed established (week 3)
- Don't mow seeded areas
- Don't skip watering (seed critical this month)
- Don't use pre-emergent (kills new seed)
Weather Reality
- Cooling; rain regular
- Perfect for growth
- Seed germinating/establishing
Your Task
Fertilize once seed established: This fertilization feeds new grass through winter
November: Root Development
What to Do
Mowing: Stop (grass dormancy approaching)
- Last mow early November only if needed
- Don't mow after mid-November
Fertilizing: None (dormancy starting)
Overseeding: Complete for year
Irrigation: Minimal (natural rainfall adequate)
Leaf cleanup: Remove leaves from lawn
- Leaves smother grass
- Rake/blow clear
Winterization: Prepare for dormancy
What to Avoid
- Don't mow after mid-November (damages dormant grass)
- Don't fertilize (won't be used)
- Don't overseed (won't germinate)
- Don't leave leaves on lawn (suffocates grass)
Weather Reality
- Cooling rapidly
- Rain heavy (winter pattern starting)
- Growth stopping
Your Task
Clean up: Prepare for dormancy with clear leaf removal
December: Dormancy & Rest
What to Do
Mowing: None (grass dormant)
Fertilizing: None
Overseeding: None
Aeration: None
Weed control: None (dormant)
Equipment prep: Clean and store equipment for winter
- Drain fuel
- Change oil
- Clean blades
Rest: Lawn dormant; minimal work
What to Avoid
- Don't mow (dormant grass)
- Don't fertilize (won't be used)
- Don't walk heavily on frozen/wet grass (causes damage)
- Don't apply anything (winter dormancy)
Weather Reality
- Cold, wet (peak winter)
- Grass brown; dormant (normal)
- Holiday season
Your Task
Rest: Your lawn is resting; you should too
PNW-Specific Notes
The Fall Overseeding Window (Sept 15–Oct 1)
Why this window is critical:
- Soil temps ideal (60–70°F)
- Natural rainfall starts (no watering labor)
- Seeds germinate in 7–10 days
- Roots develop 8 weeks before dormancy
- Spring = thick, established lawn
This single month determines next year's lawn quality.
Spring Aeration (April)
Why spring is secondary:
- Breaks winter compaction
- Enables spring root growth
- Not as critical as fall
But if you can only aerate once yearly, do FALL, not spring.
Heavy Fall Fertilization (Late October)
Why this is the most important feeding:
- New seedlings need nutrition
- Established grass stores nutrients for winter
- Spring growth depends on fall feeding
- Increases winter hardiness
Skip spring fertilizer; do fall fertilizer.
PNW Drainage Note
Wet springs common → aerate as soon as soil drains (avoid wet aeration)
Dry summers → water 1–2x per week depending on rain
Mild winters → grass may never fully go dormant; minimal winter mowing possible
Quick Reference: Task by Month
| Month | Mow | Fertilize | Overseed | Aerate | Herbicide | |-------|-----|-----------|----------|--------|-----------| | Jan | ❌ | ❌ | ❌ | ❌ | ❌ | | Feb | ❌ | ❌ | ❌ | ❌ | ❌ | | Mar | ✅ (late) | ✅ (light) | ❌ | ❌ | ⚠️ (pre-em) | | Apr | ✅ | ✅ (light) | ❌ | ✅ CRITICAL | ✅ (spot) | | May | ✅ | ❌ | ❌ | ✅ (finish) | ✅ (spot) | | Jun | ✅ | ❌ | ❌ | ❌ | ✅ (spot) | | Jul | ⚠️ (bi-weekly) | ❌ | ❌ | ❌ | ❌ | | Aug | ✅ | ❌ | PREP | ❌ | ❌ | | Sep | ✅ | ❌ | ✅ CRITICAL | ✅ CRITICAL | ❌ | | Oct | ⚠️ (ease back) | ✅ CRITICAL | (complete) | ❌ | ❌ | | Nov | ✅ (early only) | ❌ | ❌ | ❌ | ❌ | | Dec | ❌ | ❌ | ❌ | ❌ | ❌ |
Annual Cost Estimate
DIY Approach:
- Aeration rental (2x): $80–100
- Seed (fall): $50–100
- Fertilizer (3 applications): $100–150
- Total: $250–350
Professional Approach:
- Aeration (2x): $150–400
- Overseeding: $200–400
- Fertilization (3x): $200–400
- Total: $550–1,200
FAQ: Lawn Care Schedule
Q: When's the best time to overseed? A: Sept 15–Oct 1 (fall only for PNW). Spring fails.
Q: Can I fertilize in summer? A: No. Wait for fall (most important). Spring light application only.
Q: When should I aerate? A: April (spring) or September (fall). Fall is more critical.
Q: Is monthly maintenance needed? A: No. Follow this seasonal schedule; you'll be ahead of 90% of homeowners.
Q: What if I only have time for one aeration yearly? A: Do fall (September). Spring is secondary.
Conclusion
Your lawn doesn't need constant work. It needs work at the right time.
The critical months:
- April: Spring aeration (breaks compaction)
- September: Heavy aeration + overseeding (builds thick turf)
- October: Heavy fertilization (feeds new seed + prepares for winter)
The rest: Maintain, water, mow as needed.
Follow this calendar, and by next spring, you'll have a dramatically better lawn.
Need help with your lawn calendar? Contact Simply Lawn for a seasonal plan tailored to your property.