What to plant this week in Calgary, AB
With average last frost dates around May 12, most Calgarians are still waiting for the soil to thaw and warm enough before planting. The current deep freeze of Zone 4a means outdoor gardening is paused until late spring arrives.
The next 7 days
Calgary, ABGrowing in Calgary right now
- Do not attempt to sow seeds or transplant seedlings now; wait for temperatures consistently above freezing, likely after mid-May.
- Protect sensitive plants in raised beds from sudden wind chills by covering them with heavy frost blankets if a hard freeze is forecasted before May 12.
- Focus this week on preparing your garden bed soil and cleaning tools rather than active planting, as the ground will be too cold for root growth.
Sow this week
No direct sowing windows open this week.
Transplant this week
Nothing is due to go out this week.
Harvest soon
No harvest windows opening just yet.
Seasonal tips
- Finish mulching around perennials to protect crowns against late winter temperature swings.
- Test soil pH and amend beds now so nutrients are ready the moment you transplant in April.
- Start indoor seedlings of tomatoes, peppers, and eggplants under grow lights.
Pest & disease watch
- Monitor overwintering aphid colonies under tree bark; they will become a major threat once the snow melts in April.
- Watch for signs of fruit tree borers waking up from hibernation as temperatures slowly rise above freezing.
Watering this week
Keep soil lightly moist in active beds to prevent cracking, but avoid wetting dormant roots until growth resumes.
Clean up dead leaves from last season now to reduce overwintering disease spores.
Calgary gardening questions
3Should I plant my tomatoes now?
No, Calgarian gardeners should wait until after the average last frost date of May 12 before transplanting tomatoes outdoors to avoid killing them with a hard freeze.
When is the best time to sow carrots in Calgary?
Carrots can be sown directly into the ground once the soil temperature reaches at least 40°F, which typically occurs in mid-May after the frost risk has passed.
Can I grow lettuce now in Zone 4a?
Lettuce is a cool-weather crop that can be sown as soon as the ground is workable, but ensure you have a cold frame or row cover ready to protect seedlings from any late frosts near May 12.
Other cities in zone 4a
2See the full zone 4a guide → · Plan your Calgary garden in SproutGuide →