When to Plant Cauliflower in Fredericton, NB
Published: April 24, 2026 · Updated: April 27, 2026
Cool-season brassica that bolts in heat above 24°C. Start seeds indoors 4–6 weeks before last frost and transplant 2–4 weeks before last frost. Needs consistent moisture.
Fredericton's Canadian Zone 5b (USDA 5a) St. John River valley climate is continental with maritime influence. Warmer summers than coastal New Brunswick, colder winters. 151 frost-free days support a broad range of warm-season vegetables when timed carefully.
Cauliflower Planting Calendar for Fredericton
Start seeds indoors: April 5–12
Transplant outdoors: April 19–29
Harvest window: June 13 – July 28
Minimum soil temperature: 7°C (45°F)
Days to harvest: 55–100 days
Sun requirement: Full sun (6+ hours)
Fall crop planting: July 30–August 9 (harvest September 23)
⚠ Start cauliflower indoors 4–6 weeks before last frost. Transplant 2–4 weeks before last frost. Needs consistent moisture and cool temps — bolts in heat above 75°F.
Fredericton Climate Notes
Fredericton's St. John River valley creates a warmer microclimate than surrounding uplands. The city has New Brunswick's most productive growing conditions for warm-season crops. Long daylight hours in June-July produce exceptional tomato and pepper quality.
Growing Tips for Cauliflower
- Blanch white varieties by tying outer leaves over the head when it reaches egg-size — prevents yellowing from sun exposure.
- Keep soil evenly moist — drought stress causes small, bitter 'buttoning' heads instead of full curds.
- Plant fall crops in mid-July to mid-August for October harvest; fall cauliflower is usually larger and sweeter than spring.
- Use floating row covers at transplanting to block cabbage white butterflies from laying eggs.
Companion Planting in Fredericton
Pair cauliflower with Onion, Celery, Dill, Beet for mutual benefit. Avoid planting near Tomato, Strawberry, Pepper, which compete with or inhibit cauliflower growth.
Pests and Problems to Watch in Fredericton
The most common pest and disease pressure on cauliflower in Fredericton comes from Cabbage Worm, Cabbage Looper, Aphid, Flea Beetle. 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 New Brunswick Cities
Frequently Asked Questions
When do I plant cauliflower in Fredericton?
Fredericton's last spring frost is around May 10. Start seeds indoors April 5–12. Transplant outdoors April 19–29.
What Canadian hardiness zone is Fredericton?
Fredericton is in Canadian Zone 5b (USDA equivalent 5a). The St. John River valley continental maritime climate delivers 151 frost-free days from May 10 to October 8, which shapes every planting date in the local calendar.
How long is Fredericton's growing season?
Fredericton has 151 frost-free days — from May 10 in spring to October 8 in fall. That is more than enough time to finish a full cauliflower crop (55–100 days to maturity) before the first fall frost.
Can I grow cauliflower in containers in Fredericton?
Yes. Container growing on balconies and decks is practical in Fredericton — 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 Fredericton?
Fredericton's average first fall frost is October 8. For a fall cauliflower crop, plant around July 30–August 9 so plants mature before the first killing frost.