When to plant Onion in Frederick County, MD
Plant Onion in Frederick County after April 16; the prime window is April 2–April 23. A second sowing from August 14 to August 28 extends the harvest into fall.
When to Plant Onion in Frederick County, MD
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.
Frederick County, Maryland is in USDA Zone 7a. The average last spring frost is April 16 and the first fall frost is October 23, giving you a growing season of approximately 190 days.
At an elevation of 756 feet, Frederick County receives approximately 49.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89°F, providing good warmth for Onion during the growing season.
Frederick County Soil Profile
Soil Type
Silt Loam
Soil pH
5.3-6.8
Drainage
Well Drained
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 | — | 3.3" | 0" | ❄️ Dormant |
| Feb | — | 3" | 0" | ❄️ Dormant |
| Mar | — | 3.8" | 0" | ❄️ Dormant |
| Apr | 4.3" | 4.9" | 0" | ✅ Rainfall sufficient |
| May | 4.3" | 4" | 0.3" | 💧 Light watering |
| Jun | 4.3" | 4.1" | 0.2" | 💧 Light watering |
| Jul | 4.3" | 5.7" | 0" | ✅ Rainfall sufficient |
| Aug | 4.3" | 4" | 0.3" | 💧 Light watering |
| Sep | 4.3" | 4.4" | 0" | ✅ Rainfall sufficient |
| Oct | 4.3" | 4" | 0.3" | 💧 Light watering |
| Nov | — | 4.1" | 0" | ❄️ Dormant |
| Dec | — | 4.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Frederick County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Onion Planting Timeline — Frederick County, MD
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 12 | Mar 12 – Mar 26 |
| Transplant Outdoors | April 16 | Apr 16 – Apr 30 |
| Direct Sow | April 2 | Apr 2 – Apr 23 |
| Harvest | July 16 | Jul 16 – Sep 3 |
| Fall Sowing | August 14 | Aug 14 – Aug 28 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Transplant Outdoors Direct Sow |
| May | — |
| June | — |
| July | Harvest |
| August | Fall Sowing Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
Moderate — regular watering
📅 Days to Maturity
90–120 days
🧪 Soil pH
Needs 6–7 · Your soil: N/A
🗺️ USDA Zone
Zone 7a
📆 Growing Season
190 days in Frederick County
Growing Tips for Frederick County
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 Frederick County, MD?
Frederick County is in Zone 7a with an average last frost of April 16. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Frederick County, MD?
Frederick County, Maryland is in USDA Hardiness Zone 7a. The average last spring frost is April 16 and first fall frost is October 23.
When should I plant Onion in Frederick County, MD?
In Frederick County, MD, plant Onion after the last frost (around April 16) and before the first frost (around October 23). Best results when soil holds above 50°F.
What growing zone is Frederick County, MD for Onion?
Frederick County sits in USDA Zone 7a. Onion grows reliably in zones 3a through 10b, so it's a good fit here.
Can Onion grow in Frederick County's climate?
Yes — Onion grows well in Frederick County's temperate climate. Frederick County averages a 190-day frost-free season, with last frost around April 16 and first frost around October 23.
Your Frederick County Garden Planner — Free
A 22-page printable planner built for Frederick County (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.