When to Plant Onion in Chittenden County, VT
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.
Chittenden County, Vermont is in USDA Zone 4b. The average last spring frost is May 12 and the first fall frost is October 5, giving you a growing season of approximately 146 days.
At an elevation of 235 feet, Chittenden County receives approximately 38.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82°F, so choose short-season varieties of Onion to ensure they mature before fall.
Chittenden County Soil Profile
Soil Type
Silt Loam
Soil pH
4.8-6.3
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.
Plant Water Budget
Onion Planting Timeline — Chittenden County, VT
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 31 | Mar 31 – Apr 14 |
| Transplant Outdoors | May 12 | May 12 – May 26 |
| Direct Sow | May 5 | May 5 – May 26 |
| Fall Sowing | July 13 | Jul 13 – Jul 27 |
| Harvest | August 11 | Aug 11 – Sep 29 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Fall Sowing |
| August | 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
6 – 7
USDA Zone
Zone 4b
Growing Season
146 days
Growing Tips for Chittenden 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
Level Up Your Garden
Onion in Other Locations
Frequently Asked Questions
When should I plant Onion in Chittenden County, VT?
Chittenden County is in Zone 4b with an average last frost of May 12. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Chittenden County, VT?
Chittenden County, Vermont is in USDA Hardiness Zone 4b. The average last spring frost is May 12 and first fall frost is October 5.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Chittenden County gardeners in Zone 4b organize planting dates, track what's growing, and never miss a planting window.
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