Edmonton Planting Guide — Zone 4a Calendar & Frost Dates
Edmonton planting guide — Zone 4a, last frost May 14, first frost September 23, ~132-day season. Full calendar with indoor start dates and outdoor transplant dates for 20+ vegetables.
Edmonton's last frost date is May 14 — the date everything hinges on for outdoor planting. First fall frost arrives around September 23, giving Edmonton approximately 132 frost-free days. Zone 4a puts Edmonton a meaningful step above Calgary's Zone 3b, and that season length makes tomatoes, peppers, cucumbers, and even short-season sweet corn all achievable with the right timing.
This guide gives you exact planting dates for 20+ vegetables based on Edmonton's average last frost of May 14 and first fall frost of September 23. Use it alongside the seed starting calculator to generate a personalized schedule for your exact planting date.
Edmonton at a glance: Last frost May 14 · First frost September 23 · Growing season ~132 days · Hardiness zone 4a. Safe to transplant tomatoes and peppers outdoors after May 21–24. Keep frost cloth ready until June 1 for late-frost insurance.
Last Frost Date Edmonton — Historical Average
The historical average last frost date for Edmonton is May 14, based on Environment and Climate Change Canada climate normals (1991–2020). The full historical range spans from April 30 (earliest recorded) to May 28 (latest), reflecting year-to-year variation in Prairie spring weather. The forecast tracks the long-term average closely.
Edmonton's hardiness zone is 4a — slightly warmer than Calgary (3b) thanks to lower elevation and Edmonton's continental position. The frost-free growing season averages 132 days from last spring frost (May 14) to first fall frost (September 23). Edmonton's heat-island effect gives the urban core a meaningful advantage over surrounding rural Alberta — the river valley and downtown neighbourhoods are several days earlier on last frost than Sherwood Park, Spruce Grove, or St. Albert.
For frost-sensitive crops (tomatoes, peppers, basil, squash, beans), wait until May 21–24 to transplant — about a week past the average to absorb late-spring frost risk. Keep row cover or frost cloth handy through the first week of June for any unexpected cold snap. For cool-season crops (peas, lettuce, spinach, kale), sow in early to mid-May once soil reaches 4°C. Use the frost calculator for adjusted dates if you're outside Edmonton's urban core.
For a deeper dive on Edmonton's frost dates — suburb-by-suburb breakdown (St. Albert, Sherwood Park, Spruce Grove, Beaumont), Wall-O-Water and row cover techniques, and how Edmonton compares to Calgary and other Canadian cities — see the dedicated Last Frost Date Edmonton page.
📅 Edmonton's Key Frost Dates
Edmonton Planting Calendar — Full Table
All dates calculated from Edmonton's average last frost of May 14. "Start indoors" dates count backward by the recommended weeks before transplant. "Direct sow" dates are when it's safe to plant seeds directly in the garden.
| Vegetable | Start Indoors | Transplant Out | Direct Sow | Days to Harvest |
|---|---|---|---|---|
| 🍅 Tomatoes | Mar 26–Apr 9 | May 14–24 | — | 55–75 days |
| 🌶️ Peppers | Mar 15–29 | May 24–Jun 3 | — | 60–80 days |
| 🥒 Cucumbers | May 1–7 | May 21–28 | May 21–28 | 50–65 days |
| 🎃 Zucchini / Squash | May 1–7 | May 21–28 | May 21–28 | 50–60 days |
| 🌽 Sweet Corn | — | — | May 14–21 | 65–75 days |
| 🥦 Broccoli | Apr 2–16 | May 1–14 | — | 60–80 days |
| 🥬 Cabbage | Mar 26–Apr 9 | May 1–14 | — | 70–120 days |
| 🧅 Onions (from seed) | Mar 1–15 | May 1–14 | — | 100–120 days |
| 🧅 Onions (sets) | — | — | May 1–14 | 65–75 days |
| 🥕 Carrots | — | — | May 1–Jun 1 | 70–80 days |
| 🫘 Bush Beans | — | — | May 14–Jun 1 | 50–60 days |
| 🟢 Peas | — | — | Apr 21–May 7 | 55–70 days |
| 🥬 Lettuce | Apr 9–23 | May 1–14 | May 1–Jun 15 | 45–60 days |
| 🌿 Spinach | — | — | Apr 21–Jun 1 | 40–50 days |
| 🥦 Kale | Apr 2–16 | May 1–14 | May 1–Jun 1 | 55–75 days |
| 🌿 Basil | Apr 23–May 7 | May 21–28 | — | 60–90 days |
| 🌿 Parsley | Mar 15–29 | May 7–14 | May 7–14 | 70–90 days |
| 🫚 Garlic | — | — | Plant Oct 1–15 | Harvest Jul–Aug |
| 🥔 Potatoes | — | — | May 1–14 | 70–120 days |
| 🌸 Marigolds | Apr 9–23 | May 14–21 | May 14–21 | 50–60 days |
Get Your Personalized Edmonton Planting Schedule
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🌱 Free Seed Starting Calculator🍅 Growing Tomatoes in Edmonton
Edmonton's 132-day season gives tomato growers more flexibility than Calgary. You can successfully grow medium-season varieties up to 75 days — opening up a wider range of slicing and paste tomatoes. That said, short-season varieties still give the most reliable harvests and the best buffer against early September frosts.
Best Tomato Varieties for Edmonton
💡 Edmonton tip: Edmonton's May 14 last frost average means you can transplant tomatoes up to 9 days earlier than Calgary gardeners. Use that extra time wisely — an early May 14 transplant of a 52-day variety gives you a harvest window from early July to late September, well before frost risk becomes serious.
Edmonton vs Calgary: How the Seasons Compare
Both cities face short growing seasons, but Edmonton's edge is real and worth understanding — especially if you're choosing what to grow.
| Edmonton | Calgary | |
|---|---|---|
| Hardiness Zone | 4a | 3b |
| Last Spring Frost | May 14 ✓ | May 23 |
| First Fall Frost | Sept 23 ✓ | Sept 21 |
| Growing Season | ~132 days ✓ | ~120 days |
| Max tomato maturity | 75 days ✓ | 65–70 days |
| Sweet corn feasible? | Yes (65–70 day) ✓ | Risky |
Edmonton-Specific Gardening Tips
Your May 14 last frost is an average — not a guarantee
Edmonton regularly sees surprise frosts in late May. Keep frost cloth ready until June 1. Check Environment Canada's 14-day forecast before leaving tender transplants unprotected overnight — a single late-May frost can kill a full season's worth of tomato seedlings.
Use your extra days to try new crops
Edmonton's 12 extra growing days over Calgary open up crops that simply don't work further south: short-season sweet corn (Peaches & Cream, 68 days), paste tomatoes like Roma (75 days), and longer-season pepper varieties. If you've been envying what southern Alberta gardeners grow, you likely have more options than you think.
Start seeds earlier than you think you should
Many Edmonton gardeners wait too long to start seeds indoors — often not starting tomatoes until late April. By then, May 14 is only 3 weeks away, which means small, weak transplants. Start tomatoes in late March for transplants that are 6–8 weeks old and ready to hit the ground running after frost-free date.
Edmonton's river valley creates microclimates
Gardens in the North Saskatchewan River valley and its ravines are often a half-zone warmer than surrounding areas. South-facing slopes in the river valley can act like Zone 4b — giving you even more flexibility. If your garden is on a warm south-facing slope, you may be able to push variety selection a few days longer than average dates suggest.
Watch the September 23 first frost closely
Edmonton's first fall frost averages September 23, but cold years can bring frost in late August. Check forecasts starting September 1. When frost is forecast, harvest all mature tomatoes and peppers immediately. Green tomatoes ripen well indoors on a countertop — don't let a frost wipe out a week of final production.
Month-by-Month Edmonton Garden Calendar
- Start onions, leeks, celery indoors (early March)
- Start peppers indoors (mid-March)
- Start tomatoes indoors (late March)
- Order seeds and prep grow lights
- Start broccoli, cabbage, kale indoors (early April)
- Start lettuce, herbs indoors (mid-April)
- Direct sow peas outdoors under frost cloth (late April)
- Prep raised beds and garden soil
- Start cucumbers, squash, basil indoors (early May)
- Transplant cold-tolerant crops: broccoli, kale, lettuce (May 1–14)
- Direct sow carrots, spinach, peas (early May)
- Transplant tomatoes after May 14
- Harden off all seedlings (7–10 days)
- Transplant peppers and basil (early June)
- Direct sow beans (after May 24)
- Succession sow lettuce and spinach
- Keep frost cloth handy until June 1
- Harvest peas, lettuce, beans
- Harvest early tomatoes and cucumbers (late July)
- Succession sow fast crops for fall
- Keep tomatoes and peppers watered consistently
- Harvest tomatoes and peppers before Sept 23
- Bring green tomatoes indoors to ripen
- Harvest root vegetables before hard freeze
- Plant garlic (October 1–15)
- Clear and mulch beds for winter
Frequently Asked Questions
What is the last frost date in Edmonton ?
Edmonton's last frost date is May 14 (Zone 4a). For frost-sensitive crops like tomatoes and peppers, add a 1–2 week buffer and transplant outdoors around May 21–24. Always harden off transplants for 7–10 days before moving them outside.
When is the last frost in Edmonton?
Edmonton's average last spring frost is May 14. It can range from early May in warm years to late May in cold ones. Keep frost cloth ready until June 1 to protect tender transplants from late surprises.
When should I start tomatoes indoors in Edmonton?
Start tomato seeds indoors between March 26 and April 9 — 6 to 8 weeks before Edmonton's May 14 last frost date. Use the seed starting calculator for exact dates by vegetable.
What hardiness zone is Edmonton?
Edmonton is Canadian Hardiness Zone 4a — one full zone warmer than Calgary's Zone 3b. This translates to an approximately 12-day longer growing season and the ability to grow a wider range of tomato and pepper varieties.
Is Edmonton better for gardening than Calgary?
Yes — Edmonton has about 12 more frost-free days than Calgary. Last frost is 9 days earlier (May 14 vs May 23) and first fall frost is 2 days later (Sept 23 vs Sept 21). This allows Edmonton gardeners to grow 70–75 day tomato varieties that are too risky in Calgary.
Can I grow sweet corn in Edmonton?
Yes — short-season sweet corn varieties (65–75 days) can be grown successfully in Edmonton. Direct sow after May 14 when soil is warm. Choose varieties like Peaches & Cream (68 days) or Earlivee (63 days). Sweet corn is very difficult in Calgary due to the shorter season.
Trees & Shrubs for Edmonton (Zone 4)
Cold-hardy ornamental shrubs and trees for Edmonton's Zone 4a climate — native Prairie species and proven Zone 3–4 cultivars for Alberta winters.
📖 Related Guides & Calculators
Plan your Edmonton garden from seed to harvest.