When to Plant Garlic in London, ON
Published: April 24, 2026 · Updated: April 27, 2026
Garlic is planted in fall and harvested the following summer — the opposite timing from most vegetables. It is one of the most hands-off, rewarding crops once established.
London's Canadian Zone 6a (USDA 5b) southwestern Ontario climate delivers adequate rainfall, warm summers, and 170 frost-free days. Shorter than Toronto's season but long enough for reliable production of most warm-season crops with appropriate variety selection.
Garlic Planting Calendar for London
Direct sow outdoors: October–November (plant cloves)
Harvest window: June (following year) – July (following year)
Minimum soil temperature: 10°C (50°F)
Days to harvest: 240–270 days
Sun requirement: Full sun
⚠ PLANTING SEASON IS OPPOSITE: Plant garlic cloves in fall (October–November) for harvest the following summer (June–July). This is unlike any other common vegetable.
London Climate Notes
London has 150-170 frost-free days — adequate for most warm-season crops when transplants go in by late May. The region's rich soils support heavy feeders like tomatoes and brassicas with minimal amendment.
Growing Tips for Garlic
- Plant individual cloves in October–November, pointed end up, 2 inches deep, 6 inches apart.
- Mulch with 3–4 inches of straw after the first hard freeze to insulate through winter.
- Remove garlic scapes (the curling flower stalks) in June from hardneck varieties to redirect energy to the bulb.
- Harvest when the bottom 3–4 leaves turn brown — typically June in most regions.
Companion Planting in London
Pair garlic with Tomato, Rose, Carrot, Cucumber for mutual benefit. Avoid planting near Bean, Pea, Parsley, which compete with or inhibit garlic growth.
Pests and Problems to Watch in London
The most common pest and disease pressure on garlic in London comes from Thrips, White Rot, Garlic Rust, Onion Fly. Floating row covers through the first 4–6 weeks after planting block adult pests from laying eggs, and a weekly scouting routine catches infestations before they damage the crop.
Other Ontario Cities
Frequently Asked Questions
When do I plant garlic in London?
London's last spring frost is around May 3. Direct sow October–November (plant cloves).
What Canadian hardiness zone is London?
London is in Canadian Zone 6a (USDA equivalent 5b). The southwestern Ontario temperate climate delivers 170 frost-free days from May 3 to October 20, which shapes every planting date in the local calendar.
How long is London's growing season?
London has 170 frost-free days — from May 3 in spring to October 20 in fall. Garlic take 240–270 days to mature, which is tight in London's 170-day window. Choose the shortest-season varieties and protect from early fall frosts with row cover.
Can I grow garlic in containers in London?
Yes. Container growing on balconies and decks is practical in London — choose a 5-gallon or larger dark-coloured container to warm the root zone, use a high-quality potting mix, and water daily during hot summer weather. In milder climates, containers extend both spring and fall windows by several weeks.
What is the first fall frost in London?
London's average first fall frost is October 20. Most garlic in London is a single spring-timed planting designed to harvest before the first fall frost.