When to Plant Spinach in London, ON
Published: April 24, 2026 · Updated: April 27, 2026
One of the earliest spring vegetables — sow 4–6 weeks before last frost. Bolts above 75°F. Plant again in late summer for fall harvest; choose bolt-resistant varieties in warm climates.
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.
Spinach Planting Calendar for London
Direct sow outdoors: March 29–April 8
Harvest window: May 8 – May 18
Minimum soil temperature: 2°C (35°F)
Days to harvest: 40–50 days
Sun requirement: Full sun to partial shade
Fall crop planting: September 8–18 (harvest October 18)
⚠ One of the earliest spring vegetables — sow 4–6 weeks before last frost. Bolts in heat above 75°F. Plant again in late summer for a fall harvest.
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 Spinach
- Direct sow in very cold soil — spinach germinates at 35°F, earlier than almost any other crop.
- Succession plant every 10 days until 2 weeks before heat sets in for continuous spring harvests.
- Switch to bolt-resistant varieties like Malabar or New Zealand spinach for summer heat (though technically different species).
- Fall spinach often overwinters in Zones 6+, producing the earliest harvest of the next spring under row cover.
Companion Planting in London
Pair spinach with Pea, Strawberry, Radish, Lettuce for mutual benefit. Avoid planting near Fennel, which compete with or inhibit spinach growth.
Pests and Problems to Watch in London
The most common pest and disease pressure on spinach in London comes from Leaf Miner, Aphid, Downy Mildew, Slugs. 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 spinach in London?
London's last spring frost is around May 3. Direct sow March 29–April 8.
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. That is more than enough time to finish a full spinach crop (40–50 days to maturity) before the first fall frost.
Can I grow spinach 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. For a fall spinach crop, plant around September 8–18 so plants mature before the first killing frost.