When to Plant Brussels Sprouts in Moncton, NB
Published: April 24, 2026 · Updated: April 27, 2026
Fall-harvest brassica planted in midsummer. Count back 90 days from first fall frost to find your transplant date. Flavor sweetens dramatically after cold nights and light frost.
Moncton's Canadian Zone 5b (USDA 5a) climate is slightly more maritime than inland New Brunswick thanks to Bay of Fundy proximity. Cool springs, warm humid summers, and 155 frost-free days support reliable tomato crops with early starting.
Brussels Sprouts Planting Calendar for Moncton
Start seeds indoors: April 5–12
Transplant outdoors: August 2–12
Harvest window: October 21 – November 10
Minimum soil temperature: 7°C (45°F)
Days to harvest: 80–100 days
Sun requirement: Full sun (6+ hours)
Fall crop planting: July 13–23 (harvest October 1)
⚠ Brussels sprouts are planted in midsummer for a fall harvest. Count back 90 days from your first fall frost to find the transplant date. Start seeds indoors 4–6 weeks before that date. Flavor improves after frost.
Moncton Climate Notes
Bay of Fundy proximity creates a unique tidal-influenced microclimate. Moncton's summer warmth surprises many — July-August temperatures reliably support tomato crops with early starting. The Petitcodiac River valley is particularly productive for warm-season crops.
Growing Tips for Brussels Sprouts
- Count back 90 days from first fall frost to find the transplant date — this is the most important Brussels sprout timing rule.
- Pinch the top of each plant about a month before first frost — this channels energy into sprout formation.
- Harvest sprouts from the bottom up as they reach 1-inch diameter; top sprouts finish last.
- Flavor improves after the first frost — wait for cold weather before harvesting for sweetness.
Companion Planting in Moncton
Pair brussels sprout with Onion, Celery, Dill, Beet for mutual benefit. Avoid planting near Tomato, Strawberry, Pepper, which compete with or inhibit brussels sprout growth.
Pests and Problems to Watch in Moncton
The most common pest and disease pressure on brussels sprouts in Moncton comes from Cabbage Worm, Aphid, Cabbage Looper, 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.
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Frequently Asked Questions
When do I plant brussels sprout in Moncton?
Moncton's last spring frost is around May 10. Start seeds indoors April 5–12. Transplant outdoors August 2–12.
What Canadian hardiness zone is Moncton?
Moncton is in Canadian Zone 5b (USDA equivalent 5a). The Fundy tidal-influenced maritime climate delivers 155 frost-free days from May 10 to October 12, which shapes every planting date in the local calendar.
How long is Moncton's growing season?
Moncton has 155 frost-free days — from May 10 in spring to October 12 in fall. That is more than enough time to finish a full brussels sprout crop (80–100 days to maturity) before the first fall frost.
Can I grow brussels sprout in containers in Moncton?
Yes. Container growing on balconies and decks is practical in Moncton — 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 Moncton?
Moncton's average first fall frost is October 12. For a fall brussels sprout crop, plant around July 13–23 so plants mature before the first killing frost.