When to Plant Asparagus in Ontario
Published: April 24, 2026 · Updated: April 27, 2026
Perennial crop planted from crowns in early spring. Plant once, harvest for 20+ years. No harvest year one — light harvest year two — full harvest from year three onward.
Asparagus grow well in this province with appropriate variety selection and standard Canadian planting timing.
Asparagus Planting Window for Ontario
Direct sow outdoors: March 23–April 2
Minimum soil temperature: 10°C (50°F)
Days to harvest: 730–730 days
Sun requirement: Full sun (6+ hours)
⚠ Plant asparagus crowns in early spring as soon as soil can be worked. Plant once, harvest for 20+ years. Do not harvest first year — allow ferns to establish. Light harvest year 2, full harvest from year 3 onward.
Ontario Cities — Asparagus Planting Dates
City-specific frost dates and asparagus planting windows for Ontario.
Growing Asparagus in Ontario
- Plant one-year-old crowns in trenches 6–8 inches deep, spread roots out, and backfill gradually as ferns grow.
- Never harvest any spears the first year; allow ferns to develop and feed the crown for year-2 production.
- Cut back dead ferns in late fall and mulch heavily with 4–6 inches of compost or straw before winter.
- Once established, an asparagus bed produces for 20+ years if kept weed-free and fed with compost annually.
Companion Planting for Asparagus
In Ontario gardens, pair asparagus with Tomato, Basil, Parsley, Dill. Avoid planting near Onion, Garlic, Potato, which compete with or inhibit asparagus growth.
Common Pests and Problems
Asparagus in Ontario are commonly affected by Asparagus Beetle, Fusarium Wilt, Rust, Cutworm. Floating row covers installed at planting block most adult pests from laying eggs, and a weekly scouting routine catches infestations before they damage the crop.
Frequently Asked Questions
When should I plant asparagus in Ontario?
In Ontario (Canadian Zones 5b–6b), direct sow asparagus around March 23. Asparagus grow well in this province with appropriate variety selection and standard Canadian planting timing.
What is the best asparagus variety for Ontario?
Ontario gardeners should prioritise varieties bred for shorter seasons or Canadian climates. For asparagus in Canadian Zones 5b–6b, look for cultivars labelled under 730 days to maturity. Local nurseries and provincial seed exchanges curate varieties that ripen within Canadian frost-free windows.
How does Ontario's climate affect asparagus?
Ontario spans Canadian Zones 5b–6b with frost-free seasons ranging from roughly 153 to 195 days. Asparagus actually prefer the cooler spring and fall windows typical of Ontario, making them one of the most reliable crops in the province.
Can I grow asparagus in containers in Ontario?
Yes. Container growing on balconies and patios extends the viable growing area across every Canadian province. Dark-coloured containers warm up faster in spring and extend the season on both ends. Choose a 5-gallon or larger pot for asparagus and water daily during hot summer weather, since containers dry out quickly.
When is the first fall frost in Ontario?
First fall frost dates in Ontario range from October 15 in the coldest areas to November 1 in the warmest. Most asparagus plantings in Ontario are spring-timed to harvest before the first fall frost rather than as a second fall crop.