When to Plant Fall Flowers in Ottawa, ON – 2026
Published: April 27, 2026
Ottawa is in Canadian Zone 5b (continental inland). Last spring frost averages May 6; first fall frost October 6; the growing season runs about 153 frost-free days. Plant fall flowers in Ottawa from spring planting (after victoria day) for fall bloom; nursery mums in august-september..
Fall Flowers Planting Window for Ottawa, ON
Plant fall-blooming mums, asters, and sedums in spring or early summer for fall bloom. Fall-planted pansies and ornamental kale provide color into November in Zones 6+. Plant bulbs for next fall: dahlias in spring; tulips in fall.
For Ottawa, ON specifically, the recommended planting window is Spring planting (after Victoria Day) for fall bloom; nursery mums in August-September.. Ottawa Valley winters are harsh. Choose short-season tomato varieties under 70 days (Stupice, Sunrise, Sub-Arctic Plenty) and transplant only after the May long weekend. Fall garden extends the productive season into October with cold-tolerant greens and brassicas.
Hardy mums (Chrysanthemum) and asters are reliably hardy to Zone 4 with proper fall preparation — choose varieties bred for Canadian winters. Pot mums sold at Canadian Tire in September are often NOT cold-hardy and should be treated as annuals.
Best Fall Flowers Varieties for Ottawa, ON
For Ottawa, ON (Canadian Zone 5b), choose varieties rated for your zone or one zone colder for reliable winter survival. The Canadian-bred or tested varieties below perform well in Ontario conditions.
Bred for Canadian Prairie winters. The most reliable mums for Calgary, Edmonton, Saskatoon, Regina, Winnipeg.
Hybrid Korean × hardy mums. Reliable Prairie performance with longer bloom period than standard hardy mums.
Native Canadian fall-blooming aster. Reliable to Saskatoon. Strong pollinator value.
Drought-tolerant succulent perennial. Pink-bronze blooms in September. Excellent across all Canadian zones.
Cool-season annuals planted in late summer for fall colour. Continue blooming through October frost in Ontario and BC.
How to Plant Fall Flowers in Ottawa
Sow method: transplant (summer planting for fall bloom). The steps below adapt the general planting advice for Ottawa, ON's climate and timing.
- →Plant fall-blooming perennials (mums, asters, sedums) in spring (April through June) for established root systems before fall bloom.
- →Plant fall-blooming bulbs (saffron crocus, autumn crocus, fall-blooming species cyclamen) in summer (July through August).
- →Plant cool-season annuals (pansies, ornamental kale) in late summer through early fall for immediate cool-weather color.
- →Pinch growing tips of mums in early summer to encourage bushier growth and more fall blooms.
- →Choose full sun (6+ hours) for mums, asters, and sedums; part shade for pansies in Zone 7+.
- →Water consistently during establishment; once established, fall perennials are drought-tolerant.
Frequently Asked Questions about Fall Flowers in Ottawa, ON
When can I plant fall flowers in Ottawa?
Plant fall flowers in Ottawa from spring planting (after victoria day) for fall bloom; nursery mums in august-september. based on the city's Canadian Zone 5b. Last spring frost: May 6; first fall frost: October 6; frost-free growing season: 153 days.
What Canadian zone is Ottawa?
Ottawa is in Canadian Zone 5b (USDA equivalent 5a). The climate is continental inland. Ottawa Valley winters are harsh. Choose short-season tomato varieties under 70 days (Stupice, Sunrise, Sub-Arctic Plenty) and transplant only after the May long weekend. Fall garden extends the productive season into October with cold-tolerant greens and brassicas.
Are fall flowers winter-hardy in Ottawa?
Hardy mums (Chrysanthemum) and asters are reliably hardy to Zone 4 with proper fall preparation — choose varieties bred for Canadian winters. Pot mums sold at Canadian Tire in September are often NOT cold-hardy and should be treated as annuals.