When to Plant Onion in Sarnia-Lambton, ON
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.
Sarnia-Lambton, Ontario is in USDA Zone 7b. The average last spring frost is April 3 and the first fall frost is October 27, giving you a growing season of approximately 207 days.
At an elevation of 590 feet, Sarnia-Lambton receives approximately 39.1 inches of rainfall annually with predominantly clay loam soil. Summer highs average 84°F, so choose short-season varieties of Onion to ensure they mature before fall. Clay soil retains moisture well for Onion, but amend with compost to improve drainage and prevent root rot.
Sarnia-Lambton Soil Profile
Soil Type
Clay Loam
Soil pH
6.0-7.0
Drainage
Well Drained
Onion Planting Timeline — Sarnia-Lambton, ON
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 27 | Feb 27 – Mar 13 |
| Transplant Outdoors | April 3 | Apr 3 – Apr 17 |
| Direct Sow | March 20 | Mar 20 – Apr 10 |
| Harvest | July 3 | Jul 3 – Aug 21 |
| Fall Sowing | August 18 | Aug 18 – Sep 1 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors Direct Sow |
| April | Transplant Outdoors Direct Sow |
| May | — |
| June | — |
| July | Harvest |
| August | Fall Sowing Harvest |
| September | Fall Sowing |
| 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 7b
📆 Growing Season
207 days in Sarnia-Lambton
Growing Tips for Sarnia-Lambton
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 Sarnia-Lambton, ON?
Sarnia-Lambton is in Zone 7b with an average last frost of April 3. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Sarnia-Lambton, ON?
Sarnia-Lambton, Ontario is in USDA Hardiness Zone 7b. The average last spring frost is April 3 and first fall frost is October 27.
Your Sarnia-Lambton Garden Planner — Free
A 22-page printable planner built for Sarnia-Lambton (Zone 7b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.