Ontario · Growing Zone 5a
Gardeners in Sudbury, ON can expect the average last spring frost around May 18, and the first fall frost around September 29, based on historical Environment Canada frost data for the area. That gives Sudbury a frost-free growing season of roughly 134 days. Actual frost dates shift by a week or two year to year, so use this as a planning baseline rather than an exact guarantee, and always check your local forecast before moving tender plants outside.
You have your Sudbury frost dates. Now put them to work: GrowBlock counts back your indoor seed-starting weeks, marks your safe planting day, warns you before a frost, and lays your whole season out on one timeline.
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Most warm-season crops (tomatoes, peppers, squash) need transplanting only after the last frost has passed, and are usually started indoors 6 to 8 weeks before that date. Cold-hardy crops (peas, lettuce, spinach) can often go in the ground a few weeks before the last frost. As Sudbury's first fall frost approaches in September, it's time to plan the last harvests for anything frost-sensitive still in the ground.
Approximate dates for common crops in Sudbury, worked out from the local last frost around May 18. Warm crops go out after frost, cold-hardy crops a few weeks before it, and anything with an indoor start is counted back from its sow date.
| Crop | Start indoors | Sow / transplant out | Approx. harvest |
|---|---|---|---|
| 🍅 Tomato | April 13 | June 1 | August 20 |
| 🌶️ Pepper | March 30 | June 1 | August 15 |
| 🥒 Cucumber | — | May 25 | July 22 |
| 🥬 Zucchini | — | May 25 | July 14 |
| 🥬 Lettuce | — | April 27 | June 11 |
| 🥬 Spinach | — | April 27 | June 14 |
| 🫛 Peas | — | April 27 | June 28 |
| 🥕 Carrots | — | April 27 | July 4 |
| 🫘 Bush beans | — | May 18 | July 7 |
| 🥬 Kale | March 30 | April 27 | June 21 |
Guideline dates from Sudbury's average frost window, not a guarantee. GrowBlock tunes these to each variety you plant and adjusts as you build your beds.
This calendar is a starting point. In GrowBlock every date is tuned to the exact varieties you plant and updates as you lay out your beds, and you can share the plan with whoever you garden with, changes show up for both of you.
Build your Sudbury garden planAround May 18 on average, though it can vary by a week or two either way depending on the year.
Sudbury is in zone 5a, with a frost-free season of about 134 days.
Now that you have your dates, here is how to put them to work through the season:
More how-to on the GrowBlock gardening blog.
See frost dates for all Canadian cities covered by GrowBlock.