Moncton Planting Guide — Zone 5b Calendar & Frost Dates
Moncton planting guide — Zone 5b, last frost May 15, first frost September 28, ~136-day season. Full calendar with indoor start dates and outdoor transplant dates for 20+ vegetables.
Moncton's last frost date is May 15 — the date that determines your entire planting schedule. First fall frost arrives around September 28, giving Moncton approximately 136 frost-free days in Zone 5b. The Petitcodiac River and Bay of Fundy provide modest moderation; the Acadian coast (Shediac, Cap-Pelé) gets 2–4 extra days, while inland communities (Salisbury, Sussex) run 5–10 days later.
For a deeper dive on Moncton's frost dates — Greater Moncton community-by-community breakdown (Dieppe, Riverview, Shediac, Sackville NB), Acadian coast Bay of Fundy moderation, Tantramar marsh microclimate, and how Moncton compares to Halifax and Fredericton — see the dedicated Last Frost Date Moncton page. Use this guide alongside the seed starting calculator to build your full planting schedule.
Moncton at a glance: Last frost May 15 · First frost Sept 28 · Growing season ~136 days · Hardiness zone 5b. Cool-season crops (peas, spinach, lettuce, kale) start mid-April; brassicas + onions transplant early May; warm-season crops (tomatoes, peppers, beans, cucumbers) after May 25.
📅 Moncton's Key Frost Dates
Moncton Planting Calendar — Full Table
All dates calculated from Moncton's average last frost of May 15. Start indoors dates count backward from transplant date. Direct sow dates are when it's safe to plant outdoors.
| Vegetable | Start Indoors | Transplant Out | Direct Sow | Days to Harvest |
|---|---|---|---|---|
| 🍅 Tomatoes | Apr 3–17 | May 25–Jun 1 | — | 55–75 days |
| 🌶 Peppers | Mar 20–Apr 3 | May 28–Jun 5 | — | 60–80 days |
| 🥬 Cucumbers | May 1–8 | May 22–30 | May 22–30 | 50–65 days |
| 🎃 Zucchini / Squash | May 1–8 | May 22–30 | May 22–30 | 50–60 days |
| 🥦 Broccoli | Apr 10–24 | May 6–15 | — | 60–80 days |
| 🥭 Cabbage | Apr 3–17 | May 6–15 | — | 70–120 days |
| 🧀 Onions (seed) | Mar 6–20 | May 6–15 | — | 100–120 days |
| 🧀 Onions (sets) | — | — | May 6–15 | 65–75 days |
| 🥕 Carrots | — | — | May 1–Jun 5 | 70–80 days |
| 🫘 Bush Beans | — | — | May 22–Jun 10 | 50–60 days |
| 🌿 Peas | — | — | Apr 20–May 5 | 55–70 days |
| 🥕 Lettuce | Apr 17–May 1 | May 6–15 | Apr 25–Jun 20 | 45–60 days |
| 🍃 Spinach | — | — | Apr 25–May 25 | 40–50 days |
| 🥦 Kale | — | — | Apr 25–May 15 (+ Aug for fall) | 55–75 days |
| 🪒 Radishes | — | — | Apr 20–Jun 15 | 25–35 days |
| 🥔 Potatoes (seed) | — | — | Apr 25–May 15 | 70–100 days |
| 🥦 Garlic (hardneck) | — | — | Oct 1–15 (previous year) | Harvest Jul–Aug |
Moncton Month-by-Month Planting Tasks
🌚 March
- Start onion seeds indoors (week 2)
- Start pepper seeds indoors (week 3–4)
- Order seed potatoes and tender bedding plants
🌿 April
- Start tomato seeds indoors (early-to-mid month)
- Start broccoli, cabbage, lettuce indoors (mid-month)
- Direct sow peas, radishes, spinach outdoors (late month)
- Prepare beds — compost amendment
🌺 May
- Plant seed potatoes (week 1–3)
- Transplant brassicas, onions, lettuce (week 1–3)
- Direct sow carrots, kale, beets (early month)
- Transplant tomatoes, peppers, cucumbers, zucchini (after May 25)
- Direct sow bush beans (after May 22)
🍅 June
- Finish warm-crop transplants (week 1)
- Direct sow last beans, cucumbers, zucchini (week 1–2)
- Side-dress with compost
- Mulch heavily for moisture retention
☀️ July–August
- Harvest peas, lettuce, radishes, garlic
- Start fall brassicas indoors (July)
- Direct sow fall kale, spinach, lettuce (early August)
- Watch for late blight on tomatoes (Maritime humidity)
🍁 September–October
- Main harvest: tomatoes, peppers, beans, squash (Sept)
- Cover frost-sensitive crops with row cover (late Sept)
- Plant hardneck garlic (Oct 1–15)
- Mulch garlic beds heavily for overwintering
Best Vegetables for Moncton's Climate
Moncton's humid continental climate with Bay of Fundy moderation favours cool-season crops: kale, peas, broccoli, cabbage, spinach, lettuce, and root vegetables (carrots, beets, potatoes). The Tantramar dyked land near Sackville NB is some of the best agricultural land in the Maritimes for cool-season vegetables.
Warm-season crops succeed with proper variety selection. For tomatoes, pick short-season varieties (55–75 days): Bush Beefsteak, Manitoba, Scotia, Glacier. For peppers, choose 60–75 day varieties and start indoors in mid-March. Cucumbers and zucchini thrive in the warm Moncton July–August. Bay of Fundy humidity creates some late blight pressure — stake tomatoes for airflow and avoid overhead watering.
Hardneck garlic planted in mid-October overwinters reliably under Moncton's snow cover and produces excellent heads — the Maritimes are reputed for high-quality garlic production. The Acadian coast and the Memramcook valley have a tradition of garlic farming worth tapping.
Maritime Late Frost Protection
A late frost after May 15 happens roughly 1 year in 5 in Greater Moncton, more often in Salisbury and Sussex (inland). Maritime late frosts are usually -1 to -3°C and arrive with cold Atlantic rain or wet snow rather than the dry radiation frosts of inland Quebec or the Prairies. Keep floating row cover (Reemay, Agribon) on hand until at least May 25 — the Maritime workhorse for spring frost protection. Cloches over individual seedlings on forecast frost nights. Plant tender crops against a south-facing fence or in a Tantramar dyked field for marsh moderation. Watch the 10-day forecast: don't transplant tender crops if nights below 5°C are forecast within 7 days.
📍 Atlantic Canada Garden Resources
Plan Your Moncton Garden Season
Use the frost calculator for your exact postal code — Acadian coast (Shediac) runs 2–4 days earlier than the May 15 Moncton average; inland Sussex runs 5–10 days later.