When to Plant Alliums in Sherbrooke, QC
Ornamental alliums (Allium spp.) bridge the gap between spring and summer with their striking globe-shaped flower heads in shades of purple, violet, white, and pink. Blooming after tulips have faded, they extend the spring display well into early summer. 'Gladiator', 'Globemaster', and 'Purple Sensation' produce softball-sized heads on 18–36 inch stems, while smaller species create charming accents at border fronts. Deer and rodents shun them completely due to the characteristic onion scent. Dried seed heads provide architectural interest into fall.
Sherbrooke, Quebec is in USDA Zone 5b. The average last spring frost is April 23 and the first fall frost is October 7, giving you a growing season of approximately 167 days.
At an elevation of 738 feet, Sherbrooke receives approximately 30.7 inches of rainfall annually with predominantly gray-brown podzol soil. Summer highs average 74°F, so choose short-season varieties of Alliums to ensure they mature before fall.
Sherbrooke Soil Profile
Soil Type
Gray-Brown Podzol
Soil pH
6.0-7.0
Drainage
Well Drained
Alliums 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.
How to Plant Alliums
Fall planting: Sow 6 weeks before your first frost date for a fall harvest.
Alliums Water Budget
Monthly Watering Guide for Alliums
Alliums needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.
| Month | Alliums Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.4" | 0" | ❄️ Dormant |
| Feb | — | 1.2" | 0" | ❄️ Dormant |
| Mar | — | 2.3" | 0" | ❄️ Dormant |
| Apr | 2.2" | 3" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 3.9" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 4.1" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 3.4" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 2.7" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 2.6" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 2.1" | 0.1" | 💧 Light watering |
| Nov | — | 2" | 0" | ❄️ Dormant |
| Dec | — | 1.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Sherbrooke). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Alliums 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.
Alliums Planting Timeline — Sherbrooke, QC
Alliums Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Bloom | September 30 | Sep 30 – Oct 21 |
| Fall Sowing | August 26 | Aug 26 – Sep 9 |
Plant 5" deep · 7" apart · Rows 8" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | — |
| June | — |
| July | — |
| August | Fall Sowing |
| September | Fall Sowing Bloom |
| October | Bloom |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
28–42 days
🧪 Soil pH
Needs 5.5–7.5 · Your soil: N/A
🗺️ USDA Zone
Zone 5b
📆 Growing Season
167 days in Sherbrooke
Growing Tips for Alliums in Sherbrooke
Your generous 167.0-day season in Sherbrooke allows multiple plantings of Alliums. Sow every 14.0 days for continuous harvest.
Common pests for Alliums in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.
General growing tips
Plant bulbs in fall, 3–4 times as deep as the bulb diameter (typically 4–6 inches for large types, 3 inches for small species). Space 6–8 inches apart for standard cultivars. Foliage often looks untidy as it dies back before bloom — plant around perennials that will conceal the yellowing leaves. Excellent drainage is essential; alliums rot in wet soils. Leave bulbs in place for naturalization; divide every 3–4 years when clusters become congested. Deadhead spent globes or leave for ornamental seedheads and self-sowing.
Companion Planting
Good Companions
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Check more plant combinations with our Companion Planting Checker →
Alliums in Other Locations
Frequently Asked Questions
When should I plant Alliums in Sherbrooke, QC?
Sherbrooke is in Zone 5b with an average last frost of April 23. Plan your Alliums planting based on this frost date — see the calendar above for exact timing.
What planting zone is Sherbrooke, QC?
Sherbrooke, Quebec is in USDA Hardiness Zone 5b. The average last spring frost is April 23 and first fall frost is October 7.
Your Sherbrooke Garden Planner — Free
A 22-page printable planner built for Sherbrooke (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.