Can I grow two crops of broccoli in Ontario?

Yes — two crops per season are achievable in most of Ontario, and this is the ideal approach. The spring crop is started indoors in February–March and harvested June–July before summer heat causes it to bolt. The fall crop is started indoors in late June to early July and transplanted in late July or early August — it matures in the cooling temperatures of September and October and is often the better-tasting of the two harvests. Broccoli actually prefers cool fall temperatures for heading, making the fall crop particularly reliable across Ontario. Ottawa's shorter season makes fall timing tighter — a second crop is possible but requires precise scheduling.

What are the best broccoli varieties for Ontario?

Calabrese (78 days) is the classic heading broccoli — large central head followed by sideshoots that extend the harvest. Green Magic (60 days) is an excellent fast-maturing hybrid suited to Ontario's spring crop window. Belstar (65 days) is a popular fall crop variety with outstanding flavour in cool weather. Gypsy (58 days) is the fastest-maturing option — best for Ottawa and Kingston's shorter season or for fall crops with tighter timing. Waltham 29 (80 days) is a reliable open-pollinated variety popular with Ontario home gardeners. For fall crops, choose varieties with tighter maturity windows — Gypsy and Belstar are ideal.

Why is my broccoli bolting or forming small heads?

The most common cause in Ontario is heat. Broccoli is a cool-season crop that heads poorly when temperatures exceed 27°C consistently — which Ontario's July and August regularly deliver. Bolting (forming yellow flowers instead of a tight head) happens when the plant experiences sustained heat stress. Prevention: time your spring crop to harvest in June before peak heat; ensure your fall crop is timed to head in September when temperatures have dropped. Planting too early and having broccoli head in the August heat is the #1 Ontario broccoli mistake. The fall crop, heading in September–October, consistently produces better quality heads than the spring crop in Ontario.

How do I care for broccoli in Ontario?

Broccoli needs consistent moisture — irregular watering causes hollow stems and poor head development. Water deeply twice a week, more during hot dry spells. Fertilise at transplanting with a balanced fertiliser and again when heads begin to form. Watch for cabbage worms (small green caterpillars that eat foliage) — the most common Ontario broccoli pest. Row cover (floating fabric) from transplant through harvest is the most effective cabbage worm control. Harvest the central head when tight and before any yellow colour appears — once you see yellow the head is past peak. Leave the plant in the ground — sideshoots will continue producing smaller florets for weeks after the central harvest.

When do I harvest broccoli in Ontario?

Harvest the central head when it is firm and dark green, before any buds begin to open or show yellow. Once you see yellow, the broccoli is past peak and will taste bitter. Spring crop: harvest June–July depending on your city and start date. Fall crop: harvest September–October. After the central head is cut, leave the plant in the ground — sideshoots will produce smaller florets continuously for 4–6 weeks. Fall-harvested broccoli that survives light frosts actually improves in flavour — frost converts starch to sugar, producing noticeably sweeter broccoli.

ONTARIO PLANTING GUIDE

When to Plant Broccoli in Ontario — 2026 Guide

Q: When should I plant broccoli in Ontario?

Broccoli is a cool-season crop planted twice in Ontario — a spring crop and a fall crop. Spring planting: start seeds indoors 6–8 weeks before last frost and transplant outdoors 4 weeks before last frost (broccoli tolerates frost). Toronto/Windsor: start indoors February 15–March 1, transplant late March to April 1. Ottawa: start indoors March 1–15, transplant April 10–25. Fall planting: count back 80 days from first fall frost and start indoors that number of days plus 6 weeks. Toronto fall crop: start indoors July 1, transplant outdoors July 25–August 1. Ottawa fall crop: start indoors June 20, transplant July 15.

Two crops per season across most of Ontario. Indoor start dates, transplant timing, and fall crop scheduling for Toronto, Ottawa, Hamilton, Windsor, and Kingston.

Broccoli is one of the most rewarding vegetables for Ontario gardeners because the climate supports two complete crops per season. The spring crop harvests in June before Ontario's summer heat arrives. The fall crop — started indoors in late June or July and transplested in late July — matures in the cool temperatures of September and October and consistently produces higher-quality heads than the spring crop.

The key to both crops is timing. Broccoli that heads in Ontario's peak summer heat (July–August) produces small, bitter, loose heads. Broccoli that heads in June or September–October produces the firm, sweet, supermarket-quality heads you're aiming for.

Ontario broccoli at a glance: Two crops possible. Spring crop: start indoors Feb–Mar, transplant 4 weeks before last frost, harvest June–July. Fall crop: start indoors late June–July, transplant late July–Aug, harvest Sept–Oct. Fall crop tastes better. Frost improves flavour.

Outside Ontario? See the Canada-wide broccoli planting guide for dates in BC, Quebec, the Prairies, and the Maritimes — plus why fall outperforms spring in most regions.

Ontario Broccoli Dates by City — Spring & Fall Crops

City	Spring: Start Indoors	Spring: Transplant	Spring: Harvest	Fall: Start Indoors	Fall: Transplant	Fall: Harvest
Windsor	Feb 10–25	Mar 22–Apr 5	May 25–Jun 15	Jul 5–15	Aug 1–10	Oct–Nov
Toronto	Feb 15–Mar 1	Mar 25–Apr 5	Jun 1–25	Jul 1–15	Jul 25–Aug 5	Oct
Hamilton	Feb 20–Mar 5	Mar 28–Apr 10	Jun 5–25	Jul 1–15	Jul 28–Aug 8	Oct
London	Feb 25–Mar 10	Apr 1–15	Jun 10–30	Jul 1–15	Jul 28–Aug 8	Oct
Kingston	Mar 1–15	Apr 5–20	Jun 15–Jul 5	Jun 25–Jul 5	Jul 20–Aug 1	Sept–Oct
Ottawa	Mar 1–15	Apr 10–25	Jun 20–Jul 10	Jun 20–Jul 1	Jul 15–25	Sept–Oct

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Why the Fall Crop Is Better

Frost improves flavour

Light frosts below -2°C convert starch in broccoli heads to sugar. Fall broccoli that has experienced a few October frosts is noticeably sweeter than spring-harvested broccoli. Ontario's reliable October frosts make fall broccoli the most flavourful of the two crops.

Fewer pest problems

Cabbage moths (whose caterpillars devastate spring broccoli) have reduced populations by late summer and fall. Fall broccoli grown under row cover has minimal pest pressure compared to spring crops that contend with peak moth activity in May and June.

Better head quality

Broccoli heads form in cooling autumn temperatures after the heat of summer has passed. Cool temperatures produce tighter, more densely beaded heads. Spring broccoli that encounters a heat wave during heading produces loose, open heads that quickly bolt to flower.

Best Broccoli Varieties for Ontario

Choose varieties based on which crop you're growing — fast-maturing types for fall crops in shorter-season cities like Ottawa and Kingston, and standard types for spring crops and Toronto's longer season.

Variety	Days to Harvest	Best Use	Notes
Gypsy	58 days	Fall crop (Ottawa/Kingston)	Fastest-maturing — best for Ottawa's tight fall timing. Dense, domed heads.
Green Magic	60 days	Spring or fall	Excellent heat tolerance for spring crops. Reliable across all Ontario zones.
Belstar	65 days	Fall crop	Outstanding fall flavour. Blue-green heads. Popular at Ontario farmers' markets.
Calabrese	78 days	Spring crop (Toronto/Windsor)	Classic Italian variety with long sideshoot production after central head is cut.
Waltham 29	80 days	Spring crop (Toronto/Windsor)	Open-pollinated heritage variety. Saves seed easily. Good sideshoot production.
Di Cicco	50 days	Spring or fall	Very early, smaller heads, exceptional sideshoot production. Good for continuous harvest.

Ontario Broccoli Planting Dates by Region

Broccoli is a cool-season brassica — transplants can go out 2–4 weeks before last frost (they tolerate light frost) and the fall crop is planted in mid-summer so heads mature in cool September–October weather. Southern Ontario gets two clear crops per season; in the north a single spring crop is the safer bet.

Ontario region	Zone	Spring transplant out	Fall transplant out	Cities
Niagara / Carolinian	7a	April 5–15	July 25–August 5	St. Catharines, Niagara-on-the-Lake, Pelee Island
Southwestern ON	6b–7a	April 15–25	July 20–30	Windsor, London, Sarnia, Chatham-Kent
GTA / Golden Horseshoe	6a–6b	April 20–30	July 15–25	Toronto, Mississauga, Hamilton, Oakville
Central ON / Lake Simcoe	5a–5b	May 1–10	July 10–20	Barrie, Orillia, Peterborough, Kawartha Lakes
Eastern ON / Ottawa Valley	5a–5b	May 1–10	July 10–20	Ottawa, Kingston, Cornwall, Pembroke
Northern ON	3b–4b	May 20–June 1	Spring crop only	Sudbury, North Bay, Thunder Bay, Timmins, Sault Ste. Marie

Ontario Broccoli Pest & Problem Watchlist

Brassicas attract a predictable set of Ontario pests and stress problems. Scout twice a week — early intervention prevents the damage that ruins a head crop.

Cabbage white butterfly & cabbage worm

The #1 Ontario broccoli pest. White butterflies lay yellow eggs on leaf undersides; green caterpillars chew holes and bore into developing heads. Control: floating row cover from transplant to head formation; spray Bt (Bacillus thuringiensis) weekly once you see butterflies; hand-pick caterpillars at dusk.

Flea beetles

Tiny black jumping beetles peppering leaves with shot-hole damage in May–June. Devastating on young transplants; mature plants tolerate damage. Control: row cover for the first 3 weeks after transplant; kaolin clay spray; sticky yellow traps. Diamides as a last resort.

Cabbage maggot

Small white maggots tunnelling into the root crown of transplants — plants wilt and collapse in late May. Control: place a 12 cm cardboard collar flush to the soil around each transplant stem; rotate brassicas on a 3-year cycle; delay spring planting in heavy-pressure beds.

Club root

Soil-borne fungal disease causing swollen, distorted roots and stunted, wilting plants. Common in acidic, poorly-drained soil. Control: lime to raise pH to 7.0–7.2; 7-year rotation away from all brassicas in affected beds; never compost infected plants — bag and bin them.

Bolting & buttoning in summer heat

Heads form prematurely as small "buttons" or shoot up to flower when daytime temps stay above 25°C for a stretch. Control: choose heat-tolerant varieties (Belstar, Arcadia) for late-spring plantings; harvest spring crops by early July; time fall transplants so head formation lands in mid-September cool weather.

How to Grow Broccoli in Ontario

Soil and spacing

Broccoli is a heavy feeder that prefers fertile, well-drained soil with a pH of 6.0–7.0. Amend beds with compost before transplanting — 5 cm worked into the top 15 cm of soil is ideal. Space plants 45–60 cm apart in rows 60–75 cm apart. Wider spacing produces larger central heads; closer spacing produces more uniform smaller heads, which is often fine for home gardens. Avoid planting where other brassicas (cabbage, cauliflower, kale) grew in the previous two years.

Watering

Consistent moisture is critical — irregular watering causes hollow stems and small, loose heads. Aim for 2.5 cm of water per week, more during Ontario's hot July and August. Water at the base of plants rather than overhead — wet foliage encourages fungal disease and makes cabbage worm damage harder to spot. Mulch with 5–7 cm of straw or shredded leaves to retain moisture and regulate soil temperature, which is especially important for fall transplants going into hot August soil.

Fertilising

Apply a balanced fertiliser (10-10-10 or compost tea) at transplanting. When plants are half their final size, side-dress with a nitrogen-rich fertiliser — blood meal or a granular high-nitrogen feed. A second application when the central head begins to form speeds development. Avoid excessive nitrogen late in the season for fall crops; it pushes leafy growth at the expense of head development and reduces flavour in the cool-weather harvest.

Hardening off transplants

Broccoli transplants moved straight from a warm growing environment to Ontario's outdoor conditions — whether cold April air for spring crops or hot August sun for fall crops — suffer transplant shock that sets them back by 2–3 weeks. Harden off for 7–10 days: start with 1–2 hours outside in a sheltered spot, increasing exposure gradually. Spring transplants harden in cool conditions and handle light frost; fall transplants need shade acclimatisation from August heat before being fully exposed.

Frequently Asked Questions

When should I plant broccoli in Ontario?

Two sowings: Spring — start indoors February–March, transplant 4 weeks before last frost. Fall — start indoors late June to early July, transplant late July. Toronto spring transplant: late March to early April. Ottawa spring transplant: April 10–25. Fall crop timing is identical to spring but shifted: start indoors when spring crop is approaching harvest.

Can I grow two broccoli crops in Ottawa?

Yes — but the timing is tighter than in Toronto. Start the fall crop indoors by June 20–July 1 and transplant by July 15–25. The fall crop needs to mature by mid-October (Ottawa's first frost averages October 12). Choose a fast-maturing variety (Gypsy 58 days, Green Magic 60 days) for the fall crop in Ottawa to ensure reliable harvest before frost.

How do I stop cabbage worms from eating my broccoli?

Row cover (floating fabric) installed at transplanting and left in place through harvest is the most effective control — it physically excludes cabbage moths from laying eggs on the plants. For spring crops already infested: Bt (Bacillus thuringiensis) spray is a biological control safe for organic use. Apply to leaf undersides where eggs and young caterpillars hide. Check plants regularly and hand-remove caterpillars when found.