When to Plant Collard Greens in Mercer County, PA
Your May planting checklist for Mercer County, Pennsylvania
A quick May briefing for Mercer County, Pennsylvania gardeners — what's urgent, what's next, and what can wait.
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Time to transplant collard greens
Harden off for 7 days — a little more sun each day — before planting. That's the difference between a seedling that thrives and one that stalls.
June prep starts now
- Starting indoors: collard greens
Collard greens are a heat-tolerant member of the cabbage family with large, sturdy leaves. They are a Southern staple and one of the most nutritious leafy greens.
Mercer County, Pennsylvania is in USDA Zone 6a. The average last spring frost is May 6 and the first fall frost is October 17, giving you a growing season of approximately 164 days.
At an elevation of 63 feet, Mercer County receives approximately 43.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Collard Greens to ensure they mature before fall.
Mercer County Soil Profile
Soil Type
Silt Loam
Soil pH
5.1-6.5
Drainage
Well Drained
Plant Planting Risk Windows
Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.
Soil Compatibility in Mercer County
How your county's soil matches Collard Greens's growing requirements.
Soil pH
Your soil pH (5.1–6.5) is more acidic than Collard Greens prefers (6.0–7.0). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Mercer County is excellent for Collard Greens — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (3.5%). Annual compost additions will help Collard Greens.
How to Plant Collard Greens
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Collard Greens
Sow every 6.3 weeks. Last sowing by Aug 03 to harvest before frost.
For a dedicated fall crop, sow by Aug 08.
Plant Water Budget
Monthly Watering Guide for Collard Greens
Collard Greens needs approximately 0.8 inches of water per week (3.5" per month). Here's how your county's rainfall compares month by month.
| Month | Collard Greens Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 3.3" | 0" | ❄️ Dormant |
| Feb | — | 2.9" | 0" | ❄️ Dormant |
| Mar | — | 4" | 0" | ❄️ Dormant |
| Apr | — | 3.6" | 0" | ❄️ Dormant |
| May | 3.5" | 3.8" | 0" | ✅ Rainfall sufficient |
| Jun | 3.5" | 4.2" | 0" | ✅ Rainfall sufficient |
| Jul | 3.5" | 4.8" | 0" | ✅ Rainfall sufficient |
| Aug | 3.5" | 3.5" | 0" | ✅ Rainfall sufficient |
| Sep | 3.5" | 3.1" | 0.4" | 💧 Light watering |
| Oct | 3.5" | 3.1" | 0.4" | 💧 Light watering |
| Nov | — | 3.5" | 0" | ❄️ Dormant |
| Dec | — | 3.4" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Mercer County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Collard Greens Heat Requirements (GDD)
What are Growing Degree Days (GDD)?
Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.
Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.
Collard Greens Planting Timeline — Mercer County, PA
Collard Greens Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 1 | Apr 1 – Apr 15 |
| Transplant Outdoors | May 6 | May 6 – May 20 |
| Direct Sow | April 22 | Apr 22 – May 13 |
| Harvest | July 1 | Jul 1 – Sep 2 |
| Fall Sowing | August 8 | Aug 8 – Aug 22 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Harvest |
| August | Fall Sowing Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.8"/week · Natural rainfall sufficient
📅 Days to Maturity
55–75 days
🧪 Soil pH
Needs 6–7 · Your soil: too_acidic
🗺️ USDA Zone
Zone 6a
📆 Growing Season
164 days in Mercer County
Growing Tips for Collard Greens in Mercer County
Direct sow Collard Greens outdoors after May 06 in Mercer County when soil has warmed and frost danger has passed.
Common pests for Collard Greens in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.
General growing tips
Start seeds indoors or direct sow 4-6 weeks before last frost. Harvest lower leaves first, leaving the growing tip intact. Flavor improves after exposure to frost.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Collard Greens in Other Locations
Frequently Asked Questions
When should I plant Collard Greens in Mercer County, PA?
Mercer County is in Zone 6a with an average last frost of May 6. Plan your Collard Greens planting based on this frost date — see the calendar above for exact timing.
What planting zone is Mercer County, PA?
Mercer County, Pennsylvania is in USDA Hardiness Zone 6a. The average last spring frost is May 6 and first fall frost is October 17.
Your Mercer County Garden Planner — Free
A 24-page printable planner built for Mercer County (Zone 6a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.