When to Plant Onion in McKean County, PA
May to-do list for McKean County, Pennsylvania
May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in McKean County, Pennsylvania.
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Plant out onion
Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.
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Plant onion from seed, right in the garden
Mark the row. Birds and stray feet both have opinions about unmarked beds.
June will be here before you know it — start on
- Starting indoors: onion
Onions are a fundamental kitchen staple available in yellow, white, and red varieties. Choose long-day, short-day, or intermediate types based on your latitude.
McKean County, Pennsylvania is in USDA Zone 5b. The average last spring frost is May 18 and the first fall frost is October 4, giving you a growing season of approximately 139 days.
At an elevation of 991 feet, McKean County receives approximately 39 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Onion during the growing season.
McKean County Soil Profile
Soil Type
Silt Loam
Soil pH
5-6.7
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 McKean County
How your county's soil matches Onion's growing requirements.
Soil pH
Your soil pH (5.0–6.7) is more acidic than Onion prefers (6.0–7.0). Add garden lime to raise pH.
Soil Texture
The silt loam soil in McKean County is excellent for Onion — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Onion.
Organic Matter
Organic matter is moderate (3.1%). Annual compost additions will help Onion.
How to Plant Onion
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Plant Water Budget
Monthly Watering Guide for Onion
Onion needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Onion Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 2.7" | 0" | ❄️ Dormant |
| Feb | — | 2.2" | 0" | ❄️ Dormant |
| Mar | — | 3.5" | 0" | ❄️ Dormant |
| Apr | — | 3.6" | 0" | ❄️ Dormant |
| May | 4.3" | 3.6" | 0.7" | 💧 Light watering |
| Jun | 4.3" | 3.4" | 0.9" | 💧 Light watering |
| Jul | 4.3" | 4.2" | 0.1" | 💧 Light watering |
| Aug | 4.3" | 3.2" | 1.1" | 💧 Light watering |
| Sep | 4.3" | 3.1" | 1.2" | 💧 Light watering |
| Oct | 4.3" | 3.2" | 1.1" | 💧 Light watering |
| Nov | — | 3.1" | 0" | ❄️ Dormant |
| Dec | — | 3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in McKean County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Onion 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.
Onion Planting Timeline — McKean County, PA
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 13 | Apr 13 – Apr 27 |
| Transplant Outdoors | May 18 | May 18 – Jun 1 |
| Direct Sow | May 4 | May 4 – May 25 |
| Harvest | August 17 | Aug 17 – Oct 5 |
| Fall Sowing | July 26 | Jul 26 – Aug 9 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | Transplant Outdoors Direct Sow |
| June | Transplant Outdoors |
| July | Fall Sowing |
| August | Fall Sowing Harvest |
| September | Harvest |
| October | Harvest |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1"/week · Natural rainfall sufficient
📅 Days to Maturity
90–120 days
🧪 Soil pH
Needs 6–7 · Your soil: too_acidic
🗺️ USDA Zone
Zone 5b
📆 Growing Season
139 days in McKean County
Growing Tips for Onion in McKean County
Direct sow Onion outdoors after May 18 in McKean County when soil has warmed and frost danger has passed.
Common pests for Onion in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.
General growing tips
Start seeds indoors 8-10 weeks before transplanting. Match day-length type to your latitude. Stop watering when tops begin to fall over and cure bulbs for 2-3 weeks before storage.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Onion in Other Locations
Frequently Asked Questions
When should I plant Onion in McKean County, PA?
McKean County is in Zone 5b with an average last frost of May 18. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is McKean County, PA?
McKean County, Pennsylvania is in USDA Hardiness Zone 5b. The average last spring frost is May 18 and first fall frost is October 4.
Your McKean County Garden Planner — Free
A 24-page printable planner built for McKean County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.