In Ottawa, the average last spring frost is May 6 and the average first fall frost is Oct 1, a growing season of about 148 days (zone 5b). Start tomatoes indoors around Mar 25 and move them outside from May 20. Plant garlic Oct 8 to Oct 15, one to two weeks after the first fall frost.
Ottawa at a glance
- Last spring frost
- May 6 (average)
- First fall frost
- Oct 1 (average)
- Frost-free season
- About 148 days
- Hardiness zone
- 5b (NRCan)
- Weather stations
- Ottawa (City), Ottawa (Airport) and Angers, 1991 to 2020 normals. GrowSmart's dates are the median of these stations, to within 3 days
An average frost date means frost is still possible after it in about half of years. GrowSmart times tender crops like tomatoes, peppers and basil after this date, not on it.
What to plant in Ottawa this month (January)
Nothing is scheduled to be sown or planted in Ottawa in January. Next up: start onions indoors on Feb 25.
What to plant in Ottawa this month (February)
- Start onions indoors: Feb 25
What to plant in Ottawa this month (March)
- Start tomatoes indoors: Mar 25
- Start peppers indoors: Mar 25
- Start eggplant indoors: Mar 25
- Start lettuce indoors: Mar 25
Coming up in early April: start kale indoors (Apr 1), start broccoli indoors (Apr 1), start cabbage indoors (Apr 1) and start basil indoors (Apr 8).
What to plant in Ottawa this month (April)
- Start kale indoors: Apr 1
- Start broccoli indoors: Apr 1
- Start cabbage indoors: Apr 1
- Start basil indoors: Apr 8
- Direct sow spinach: Apr 15
- Direct sow peas: Apr 15
- Direct sow radishes: Apr 15
- Transplant lettuce: Apr 22
- Direct sow carrots: Apr 22
- Start cucumbers indoors: Apr 22
- Start zucchini indoors: Apr 22
- Start winter squash indoors: Apr 22
- Direct sow beets: Apr 29
- Transplant kale: Apr 29
- Transplant broccoli: Apr 29
- Transplant cabbage: Apr 29
- Direct sow potatoes: Apr 29
Coming up in early May: transplant onions (May 6), transplant cucumbers (May 13), transplant zucchini (May 13), transplant winter squash (May 13) and direct sow beans (May 13).
What to plant in Ottawa this month (May)
- Transplant onions: May 6
- Transplant cucumbers: May 13
- Transplant zucchini: May 13
- Transplant winter squash: May 13
- Direct sow beans: May 13
- Transplant tomatoes: May 20
- Transplant peppers: May 20
- Transplant eggplant: May 20
- Transplant basil: May 20
What to plant in Ottawa this month (June)
Nothing is scheduled to be sown or planted in Ottawa in June. Next up: sow peas for a fall harvest on Jul 23.
What to plant in Ottawa this month (July)
- Sow peas for a fall harvest: Jul 23
- Sow kale for a fall harvest: Jul 23
Coming up in early August: sow lettuce for a fall harvest (Aug 6) and sow spinach for a fall harvest (Aug 13).
What to plant in Ottawa this month (August)
- Sow lettuce for a fall harvest: Aug 6
- Sow spinach for a fall harvest: Aug 13
- Sow radishes for a fall harvest: Aug 27
What to plant in Ottawa this month (September)
Nothing is scheduled to be sown or planted in Ottawa in September. Next up: plant garlic on Oct 8.
What to plant in Ottawa this month (October)
- Plant garlic: Oct 8 to Oct 15
What to plant in Ottawa this month (November)
Nothing is scheduled to be sown or planted in Ottawa in November. Next up: start onions indoors on Feb 25.
What to plant in Ottawa this month (December)
Nothing is scheduled to be sown or planted in Ottawa in December. Next up: start onions indoors on Feb 25.
Ottawa planting calendar
| Crop | Start indoors | Plant outside | Harvest |
|---|---|---|---|
| Tomatoes | Mar 25 | Transplant May 20 | From Aug 6 |
| Peppers | Mar 25 | Transplant May 20 | From Jul 31 |
| Eggplant | Mar 25 | Transplant May 20 | From Aug 3 |
| Basil | Apr 8 | Transplant May 20 | From Jul 1 |
| Onions (from seed) | Feb 25 | Transplant May 6 | From Aug 14 |
| Lettuce | Mar 25 | Transplant Apr 22Fall: direct sow Aug 6 | From Jun 1Fall: from Sep 15 |
| Spinach | n/a | Direct sow Apr 15Fall: direct sow Aug 13 | From May 25Fall: from Sep 22 |
| Peas | n/a | Direct sow Apr 15Fall: direct sow Jul 23 | From Jun 14Fall: from Sep 21 |
| Radishes | n/a | Direct sow Apr 15Fall: direct sow Aug 27 | From May 10Fall: from Sep 21 |
| Carrots | n/a | Direct sow Apr 22 | From Jul 1 |
| Beets | n/a | Direct sow Apr 29 | From Jun 23 |
| Kale | Apr 1 | Transplant Apr 29Fall: direct sow Jul 23 | From Jun 23Fall: from Sep 16 |
| Broccoli | Apr 1 | Transplant Apr 29 | From Jul 3 |
| Cabbage | Apr 1 | Transplant Apr 29 | From Jul 8 |
| Cucumbers | Apr 22 | Transplant May 13 | From Jul 7 |
| Zucchini | Apr 22 | Transplant May 13 | From Jul 2 |
| Winter squash | Apr 22 | Transplant May 13 | From Aug 11 |
| Beans | n/a | Direct sow May 13 | From Jul 7 |
| Potatoes | n/a | Direct sow Apr 29 | From Jul 18 |
| Garlic | n/a | Plant cloves Oct 8 to Oct 15 | Around Jul 29 the next year |
Dates are for one planting of each crop, from Ottawa's average frost dates. Tomatoes are indeterminate, lettuce is looseleaf and beans are bush beans. Harvest dates are when the first picking is usually ready. Garlic follows University of Minnesota Extension (see below).
Fall planting in Ottawa
Plant garlic Oct 8 to Oct 15. That is one to two weeks after Ottawa's average first fall frost of Oct 1, the timing University of Minnesota Extension recommends, so the cloves root before winter without sending shoots up. Harvest comes around Jul 29 the following summer. How to plant garlic in Ottawa.
Shallots: GrowSmart's plan has you plant shallot sets in fall in zone 5 and warmer, and in spring in colder zones.
Cool-season crops GrowSmart schedules for a fall harvest in Ottawa:
- Peas: sow Jul 23, ready from about Sep 21
- Kale: sow Jul 23, ready from about Sep 16
- Lettuce: sow Aug 6, ready from about Sep 15
- Spinach: sow Aug 13, ready from about Sep 22
- Radishes: sow Aug 27, ready from about Sep 21
Nearby planting calendars
Ottawa planting questions
When is the last frost in Ottawa?
The average last spring frost in Ottawa is May 6, and the average first fall frost is Oct 1, from 1991 to 2020 climate normals at 3 nearby weather stations. Frost is still possible after the spring date in about half of years.
When should I start tomato seeds in Ottawa?
Start tomatoes indoors around Mar 25, 8 weeks before moving them outside around May 20, which is two weeks after the average last frost.
What can I plant in Ottawa in fall?
Garlic goes in Oct 8 to Oct 15. For fall harvests, sow peas and kale around Jul 23, lettuce around Aug 6, spinach around Aug 13 and radishes around Aug 27.