What to plant this week in Ottawa, ON
Ottawa gardeners are currently in a deep winter pause, with soil still frozen and the last frost not expected until May 8. The intense cold of Zone 5a means all outdoor planting activities must remain on hold for now.
The next 7 days
Ottawa, ONGrowing in Ottawa right now
- Keep mulch piled high around dormant perennials to shield roots from Ottawa's frequent -20°F temperature swings.
- Check your greenhouse or cold frame regularly; even with insulation, extreme lows can damage tender overwintering crops like artichokes.
- Do not attempt any soil work until the ground thaws later in May, as Ottawa clay drains poorly when frozen and thawed repeatedly.
- Prepare your seed trays indoors now if you plan to sow warm-season veggies immediately after the May 8 frost date passes.
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 clearing debris from last year's garden to reduce winter pests and diseases.
- Apply a thick layer of mulch over perennial beds once the ground has frozen solid to prevent heaving.
- Plan your spring succession schedule by calculating days-to-maturity for crops you want in early summer.
Pest & disease watch
- Snow mold can form on evergreen shrubs and mulched beds during prolonged wet snowfalls common in the Ottawa Valley winter.
- Fruit tree buds may suffer from late spring freeze damage, so monitor bud break closely as we approach the average last frost of May 8.
- Rodents will actively seek shelter under decks and sheds; secure entry points before the ground freezes solid.
Watering this week
Avoid watering the garden until the ground thaws to prevent ice formation that could damage root systems.
Now is an excellent time to sharpen your tools and organize your seed inventory so you are ready to plant immediately when the frost date passes.
Ottawa gardening questions
3When is it safe to move my potted tomatoes outside in Ottawa?
You must wait until after the average last frost date of May 8, when nighttime temperatures consistently stay above freezing for a week. Bringing them out earlier risks killing the plants due to sudden temperature drops.
Should I cover my roses with burlap this winter in Zone 5a?
Yes, Ottawa winters often dip below -20°F, which can damage unhardened rose canes even if they are dormant. Mound the base of the plant with straw and wrap it loosely to protect against extreme cold winds.
Can I harvest any vegetables right now in Ottawa?
No outdoor harvesting is possible this week as the ground is frozen and no crops have matured before winter. Your only options are indoor-grown herbs or stored root vegetables like potatoes kept in a cool basement.
Other cities in zone 5a
6See the full zone 5a guide → · Plan your Ottawa garden in SproutGuide →