When to Plant Radishes in Gatineau, QC
Published: April 24, 2026 · Updated: April 27, 2026
The fastest crop in the garden — ready in 22–30 days. Direct sow 4–6 weeks before last frost and succession plant every 2 weeks for a continuous spring harvest.
Gatineau's Canadian Zone 5a (USDA 4b) Ottawa River valley climate is virtually identical to Ottawa, Ontario across the river. Cold continental winters, warm summers, and 152 frost-free days. Reliable summer rainfall reduces irrigation demand significantly compared to drier Prairie cities.
Radishes Planting Calendar for Gatineau
Direct sow outdoors: April 1–11
Harvest window: April 23 – May 1
Minimum soil temperature: 4°C (40°F)
Days to harvest: 22–30 days
Sun requirement: Full sun to partial shade
Fall crop planting: August 31–September 10 (harvest September 22)
⚠ Direct sow radishes 4–6 weeks before last frost — one of the fastest crops in the garden. Ready in as little as 22 days. Succession plant every 2 weeks for continuous harvest.
Gatineau Climate Notes
Gatineau gardeners follow essentially the same calendar as Ottawa across the river. The Ottawa Valley receives reliable summer rainfall that reduces irrigation demand compared to drier Prairie regions. Garlic planted in October produces excellent harvests the following July.
Growing Tips for Radishes
- Thin to 2-inch spacing when seedlings are an inch tall — crowded radishes produce small woody roots.
- Succession plant every 10–14 days from early spring through late spring for continuous harvest.
- Plant as a row marker for slow-germinating crops like carrots — radishes sprout in days and mark the rows.
- Harvest promptly at target size; over-mature radishes turn pithy, woody, and unpleasantly hot.
Companion Planting in Gatineau
Pair radish with Lettuce, Carrot, Pea, Cucumber for mutual benefit. Avoid planting near Hyssop, Grape, which compete with or inhibit radish growth.
Pests and Problems to Watch in Gatineau
The most common pest and disease pressure on radishes in Gatineau comes from Flea Beetle, Cabbage Root Maggot, Aphid. 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.
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Frequently Asked Questions
When do I plant radish in Gatineau?
Gatineau's last spring frost is around May 6. Direct sow April 1–11.
What Canadian hardiness zone is Gatineau?
Gatineau is in Canadian Zone 5a (USDA equivalent 4b). The Ottawa River valley continental climate delivers 152 frost-free days from May 6 to October 5, which shapes every planting date in the local calendar.
How long is Gatineau's growing season?
Gatineau has 152 frost-free days — from May 6 in spring to October 5 in fall. That is more than enough time to finish a full radish crop (22–30 days to maturity) before the first fall frost.
Can I grow radish in containers in Gatineau?
Yes. Container growing on balconies and decks is practical in Gatineau — 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 Gatineau?
Gatineau's average first fall frost is October 5. For a fall radish crop, plant around August 31–September 10 so plants mature before the first killing frost.