When to Plant Marigolds in Ontario – 2026
Published: April 27, 2026
Ontario spans Canadian hardiness zones across multiple cities. Plant marigolds in Ontario from after victoria day (may 18 to june 1).. Marigolds are the classic Victoria Day weekend transplant in Ontario and Quebec. Buy nursery 4-pack transplants and plant out the weekend of May 18 in 2026. They begin blooming within 2 weeks of transplanting and continue through first fall frost.
Marigolds Planting Window for Ontario
Direct sow marigolds after last frost or start indoors 6–8 weeks before last frost. One of the easiest annuals — germinates in 5–7 days, blooms in 6–8 weeks. Natural pest deterrent for vegetable gardens.
For Ontario specifically, the recommended planting window is After Victoria Day (May 18 to June 1).. Ontario gardens across multiple climate zones — adjust based on your specific city. Marigolds are the classic Victoria Day weekend transplant in Ontario and Quebec. Buy nursery 4-pack transplants and plant out the weekend of May 18 in 2026. They begin blooming within 2 weeks of transplanting and continue through first fall frost.
Marigolds are tender annuals — all zones, all provinces. Frost kills them. Replant fresh seed or transplants every spring.
Ontario Cities — Marigolds Planting Dates
Each city below has local frost dates, Canadian zone, and a city-specific marigolds planting calendar.
Best Marigolds Varieties for Ontario
For Ontario , 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.
25-40 cm tall, smaller flowers, longest bloom period. Best for Canadian borders and bedding.
Largest flowers (10 cm heads) on 60-90 cm plants. Best for back-of-border in Ontario, Quebec, and Atlantic Canada.
Small daisy-like flowers, 30 cm mounding habit. Edible flowers with citrus scent.
Sterile hybrids of French × African. Longest bloom period of any marigold — bloom continuously through Canadian summer.
Perennial in BC's warmest microclimates. Used as anise-flavoured Mexican tarragon. Annual everywhere else in Canada.
Caring for Marigolds in Ontario
Sow method: direct sow or transplant. The steps below adapt the general planting advice for Ontario's climate and timing.
- →Direct sow marigold seeds 0.5 cm (1/4 inch) deep, after last frost when soil reaches 12°C (55°F).
- →For earliest blooms, start seeds indoors 6 to 8 weeks before last frost; transplant after frost.
- →Space French marigolds 15 cm (6 inches) apart; African 30 cm (12 inches); Signet 20 cm (8 inches).
- →Choose a site with full sun (6+ hours) — marigolds in shade get leggy and stop blooming.
- →Water at the base; avoid overhead watering which causes powdery mildew on Old World marigolds.
- →Deadhead spent blooms to extend the flowering period (skip for triploid hybrids — they self-clean).
Frequently Asked Questions about Marigolds in Ontario
When should I plant marigolds in Ontario?
Plant marigolds in Ontario from after victoria day (may 18 to june 1).. Direct sow marigolds after last frost or start indoors 6–8 weeks before last frost. One of the easiest annuals — germinates in 5–7 days, blooms in 6–8 weeks. Natural pest deterrent for vegetable gardens.
What Canadian zones are in Ontario?
Ontario spans multiple Canadian hardiness zones depending on location. Major cities and their zones: Toronto (Zone 6b), Ottawa (Zone 5b), Hamilton (Zone 6b), London (Zone 6a), Kitchener (Zone 6a). Check planthardiness.gc.ca for your exact postal code.
What marigolds varieties grow best in Ontario?
French marigolds (Tagetes patula) (All Canadian zones): 25-40 cm tall, smaller flowers, longest bloom period. Best for Canadian borders and bedding. African / American marigolds (T. erecta) (All Canadian zones): Largest flowers (10 cm heads) on 60-90 cm plants. Best for back-of-border in Ontario, Quebec, and Atlantic Canada.