When to Plant Cucumbers in Ottawa, ON
Published: April 24, 2026 · Updated: April 27, 2026
One of the fastest-growing vegetables — ready to harvest in 50–70 days. Cucumbers can be direct-sown after last frost and often outproduce transplanted seedlings.
Ottawa's Canadian Zone 5b (USDA 5a) continental climate brings cold winters, hot summers, and higher frost risk than Toronto thanks to the inland location. The 153 frost-free days from early May through early October is adequate for most vegetables, but variety selection — short-season cultivars under 70 days — matters significantly.
Cucumbers Planting Calendar for Ottawa
Start seeds indoors: April 15–22
Transplant outdoors: May 13–23
Direct sow outdoors: May 13–23
Harvest window: July 2 – July 22
Minimum soil temperature: 16°C (60°F)
Days to harvest: 50–70 days
Sun requirement: Full sun (8+ hours)
Fall crop planting: July 28–August 7 (harvest September 16)
Ottawa Climate Notes
Ottawa Valley winters are harsh. Choose short-season tomato varieties under 70 days (Stupice, Sunrise, Sub-Arctic Plenty) and transplant only after the May long weekend. Fall garden extends the productive season into October with cold-tolerant greens and brassicas.
Growing Tips for Cucumbers
- Direct sow after last frost rather than transplanting — cucumbers establish faster from seed in warm soil.
- Trellis vertically to save space and reduce powdery mildew from soil splash.
- Harvest every 2–3 days — cucumbers left on the vine signal the plant to stop producing new fruit.
- Water deeply and consistently; drought stress causes bitter flavor and hollow centers.
Companion Planting in Ottawa
Pair cucumber with Radish, Nasturtium, Dill, Bush Beans for mutual benefit. Avoid planting near Aromatic Herbs, Potato, Sage, which compete with or inhibit cucumber growth.
Pests and Problems to Watch in Ottawa
The most common pest and disease pressure on cucumbers in Ottawa comes from Cucumber Beetle, Squash Vine Borer, Powdery Mildew, Aphids. 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 cucumber in Ottawa?
Ottawa's last spring frost is around May 6. Start seeds indoors April 15–22. Transplant outdoors May 13–23.
What Canadian hardiness zone is Ottawa?
Ottawa is in Canadian Zone 5b (USDA equivalent 5a). The continental inland climate delivers 153 frost-free days from May 6 to October 6, which shapes every planting date in the local calendar.
How long is Ottawa's growing season?
Ottawa has 153 frost-free days — from May 6 in spring to October 6 in fall. That is more than enough time to finish a full cucumber crop (50–70 days to maturity) before the first fall frost.
Can I grow cucumber in containers in Ottawa?
Yes. Container growing on balconies and decks is practical in Ottawa — 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 Ottawa?
Ottawa's average first fall frost is October 6. For a fall cucumber crop, plant around July 28–August 7 so plants mature before the first killing frost.