When to Plant Cauliflower in Canada — Sow Dates by City
Start indoors 6–8 weeks before last frost — plus the honest reason most Canadian gardeners get better heads from a fall crop than a spring one, and how to keep white curd white.
Cauliflower is grown the same way as cabbage and broccoli — start indoors, transplant out while it's still cool — but it's far less forgiving once it's in the ground. Where cabbage just grows a bit slower under stress, cauliflower reacts to a cold snap, a dry week, or a heat spell by aborting a full head and forming a tiny "button" instead.
That sensitivity is why the real decision for Canadian gardeners isn't just "when do I sow" — it's "spring or fall." In most regions, fall wins.
Cauliflower in Canada at a glance: Start indoors 6–8 weeks before last frost. Transplant out 2–3 weeks before last frost. Toronto/Windsor: late April. Vancouver: early-to-mid March. Ottawa/Montreal: late April–early May. Calgary/Edmonton/Winnipeg: mid-May. Halifax: late April. A mid-summer-sown fall crop heads up far more reliably than spring in most regions.
When should you plant cauliflower where you garden?
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Indoor start is 6–8 weeks before last frost everywhere; transplant-out is 2–3 weeks before last frost — a slightly narrower cold-tolerance window than cabbage. Fall-sow dates below are for the more reliable second crop.
| Region (City) | Zone | Last Frost | Start Indoors | Transplant Out | Fall-Crop Sow |
|---|---|---|---|---|---|
| Coastal BC (Vancouver) | 8a | Mar 15 | Jan 20–Feb 1 | Mar 1–10 | Jun 15–Jul 1 |
| Vancouver Island (Victoria) | 8b | Mar 10 | Jan 15–25 | Feb 25–Mar 5 | Jun 15–Jul 1 |
| BC Interior (Kelowna) | 6b | May 5 | Mar 10–20 | Apr 15–22 | Jun 1–15 |
| Southern Ontario (Toronto) | 6b | Apr 20 | Feb 25–Mar 10 | Apr 1–7 | Jun 15–Jul 1 |
| SW Ontario (Windsor) | 7a | Apr 20 | Feb 25–Mar 10 | Apr 1–7 | Jul 1–15 |
| Eastern Ontario (Ottawa) | 5a | May 9 | Mar 15–25 | Apr 20–27 | Jun 1–15 |
| Quebec (Montreal) | 5b | May 9 | Mar 15–25 | Apr 20–27 | Jun 1–15 |
| Prairies (Calgary) | 3b | May 23 | Mar 25–Apr 5 | May 9–16 | May 20–Jun 1 |
| Prairies (Edmonton) | 4a | May 14 | Mar 15–25 | Apr 30–May 7 | May 20–Jun 1 |
| Prairies (Winnipeg) | 3a | May 19 | Mar 25–Apr 5 | May 5–12 | May 20–Jun 1 |
| Maritimes (Halifax) | 6a | May 10 | Mar 15–25 | Apr 20–27 | Jun 15–Jul 1 |
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🌿 Free Seed Starting CalculatorThe Universal Rules for Cauliflower (Apply Everywhere)
Favour fall over spring where you can
Cauliflower needs a stretch of steady, cool weather to form its head, and spring in most of Canada is exactly the opposite — a brief cool window that flips into summer heat right when the plant should be curding. A fall crop, sown indoors in early-to-mid summer, matures into cooling temperatures instead. If you only grow cauliflower once a year, make it the fall crop.
Never let it check — that's what causes buttoning
A cold snap, a dry spell, or transplant shock from rootbound seedlings can all trigger the plant to give up and form a tiny "button" head instead of a full one. Harden off gradually, don't let transplants get rootbound waiting to go out, and keep watering consistent — cauliflower punishes stress far more than cabbage or broccoli.
Blanch white varieties, or grow one that doesn't need it
Once the curd is egg-sized, gather the outer leaves over it and tie them in place to block sunlight — otherwise the head yellows and turns slightly bitter. Self-blanching varieties fold their own leaves over the curd as it grows, and purple, green, or orange varieties skip the step entirely.
Rotate beds — the clubroot rule applies here too
Cauliflower is a brassica, just as vulnerable to clubroot as cabbage or broccoli. Keep it out of any bed that grew a brassica in the last 3–4 years, and keep soil pH above 7.0 in regions where clubroot is a known problem.
Best Cauliflower Varieties for Canadian Gardens
| Variety | Type | Days | Why It Works |
|---|---|---|---|
| Snow Crown | Spring | 50–55 | Fast enough to beat summer heat almost anywhere in Canada. The reliable choice if you're growing spring at all. |
| Amazing | Fall | 70–75 | Large, dense heads that reward the longer, cooler runway a fall crop gets. |
| Cheddar | Spring/fall | 68 | Orange curd (extra beta-carotene) that doesn't need blanching — one less thing to manage. |
| Graffiti | Spring/fall | 80 | Deep purple, no blanching needed, and holds its colour lightly cooked. |
| Snowball Y Improved | Spring/fall | 65 | Self-blanching — its own leaves curl in over the curd as it forms, no tying required. |
Common Cauliflower Problems Across Canada
Buttoning (tiny premature heads)
Caused by any check to growth — cold shock, drought stress, rootbound transplants, or heat. Prevent it rather than fix it: harden off gradually, transplant on schedule (not early into cold soil), water consistently, and favour a fall crop in short-season regions.
Yellowed or ricey curd
Sun exposure on white varieties turns the curd yellow-green and can make it look grainy ("ricey"). Blanch by tying outer leaves over the head once it's egg-sized, or switch to a self-blanching, purple, or orange variety.
Loose, fuzzy heads instead of a tight curd
Usually heat stress during head formation. This is the core reason fall crops out-perform spring ones — the plant is curding into cooling temperatures rather than rising ones.
Clubroot
Swollen, distorted roots and stunted, wilting plants. No cure once soil is infected — prevent with a strict 3–4 year brassica rotation and soil pH above 7.0 where clubroot is a known regional problem.
Frequently Asked Questions
When should I plant cauliflower in Canada?
Start indoors 6–8 weeks before last frost; transplant out 2–3 weeks before last frost. Toronto/Windsor: late April. Vancouver: early-to-mid March. Ottawa/Montreal: late April–early May. Calgary/Edmonton/Winnipeg: mid-May.
Should I grow cauliflower in spring or fall?
Fall, if you're only growing it once. Cauliflower needs steady cool weather to head up, and a fall crop matures into cooling temperatures instead of the rising heat a spring crop runs into.
Why does cauliflower form a tiny head instead of a full one?
This is buttoning, caused by stress during growth — cold, drought, rootbound transplants, or heat. Prevent it with consistent watering and by not transplanting too early into cold soil.
Do I need to blanch cauliflower?
Only white varieties. Tie the outer leaves over the curd once it's egg-sized to keep it from yellowing in the sun — or grow a self-blanching, purple, or orange variety and skip the step.