Broccoli & Calabrese

Month on the bottom, temperature up the side. The pale green background is what the plant can survive at all -- fatal above or below it, labelled directly on the chart where that applies to your zone. The coral band is its ideal range, and only fades in during the months this zone would actually have the crop in the ground -- reusing the exact same sowing/harvesting data as the calendar further down the page. The blue line is real monthly climate data (not a modelled estimate) for a representative rural/agricultural location in this zone -- a small farming town or agricultural research station rather than a major city, to avoid the warmer bias city weather stations have. For the actual verdict on how well this crop does in your zone, see the badge at the top of the page -- that's based on the site's own researched yield figures, not this chart.

1. Sow. Direct-sow or start indoors 4-6 weeks before transplanting. Broccoli germinates readily in cool soil, down to about 4-7°C, but avoid sowing into a stretch of hot weather -- heat-stressed seedlings are more likely to button (form tiny, premature heads) later.
2. Transplant & space. Move seedlings out once they have 4-5 true leaves. Give plants about 45-60cm (18-24in) of space -- broccoli is a bigger, hungrier plant than most brassicas and resents crowding.
3. Tend through the season. Keep watering consistent, especially as the head forms -- moisture stress at this stage is the single biggest cause of small or bitter heads. Feed with a nitrogen-rich source early, then ease off once heads start forming.
4. Cut the main head. Harvest while the head is still tight and dark green, before individual yellow flower buds start to show -- typically 10-16 weeks after sowing depending on variety and climate. Cut at an angle a few centimetres below the head.
5. Keep cutting side shoots. Most varieties keep producing smaller side shoots from the leaf joints for several more weeks after the main head is cut. Once those slow down, the plant is done -- pull it and rotate the bed.

Pick your zone under "Temperature Range by Month" above and this updates too. The Sow row: green is the normal safe sowing window, amber is pushing the season by roughly a month either side with basic outdoor protection (cold frame, fleece, cloche), blue is starting seed indoors or under glass for an even earlier transplant. The Harvest row shows the main-head window -- unlike kale, broccoli doesn't stand in the ground through winter waiting to be picked, so there's no extended "still pickable" tail here. Once that window closes (and you've worked through any side-shoot flush after the main head), that planting is finished.

Broccoli is a nutrition crop, not a calorie staple -- about 340 kcal per kg, similar to kale and well below true calorie staples. Grow it for vitamin C, folate and fibre, and let calorie-dense crops carry the bulk of your energy needs.

Figures per plant sown, from the site's own crop database. Arid-zone figures already include the 60% yield penalty the calculator applies to "challenging" growing seasons there -- broccoli is grown through the cool season in Arid zones specifically to dodge the heat. Maritime, Mediterranean, Subtropical and Continental all tie numerically, but the crop database singles out Maritime as the most reliable of the four.

Broccoli varieties differ in earliness, side-shoot production and cold tolerance. All the varieties below are open-pollinated (OP), meaning seed saved from them breeds true and is worth keeping under this site's seed-saving approach; none are F1 hybrids.

Broccoli crosses freely with kale, cauliflower, cabbage, Brussels sprouts and kohlrabi -- all one species (Brassica oleracea). It's also biennial, and since the part you eat is the unopened flower head, saving seed means reserving whole plants that are never harvested.

Broccoli has essentially no storage life at ambient temperature -- cut heads start losing quality within days, and the crop database's own figures reflect that (0 weeks storable, fresh use only). Refrigerated, a cut head keeps about 3-5 days before quality drops off fast.

For real preservation: blanch and freeze is by far the most reliable method, and broccoli freezes exceptionally well, holding good texture and colour for 10-12 months. It can also be pickled (chopped florets in a vinegar brine) or fermented, though both change the texture more than freezing does. Unlike kale, there's no "leave it in the garden" storage option here -- once a head is ready, cut it.

Broccoli shares the same pest profile as the rest of the brassica family -- cabbage white caterpillars, flea beetle, aphids -- and exactly which one causes trouble depends heavily on where you are. What works almost everywhere instead:

Floating row covers or fine insect netting are the single most effective input-free defence -- they physically exclude the large majority of common brassica pests regardless of which one is active locally, with no identification needed.

Companion planting helps too: aromatic herbs like dill, oregano or thyme interplanted nearby mask the scent brassica pests use to find their host, and nasturtiums nearby often draw pests away as a sacrificial trap crop.

Crop rotation matters as much as pest defence -- avoid growing broccoli, or any brassica, in the same bed two years running. This breaks the life cycle of soil-borne problems like clubroot, which can persist in soil for years without a host to reset the clock.

Consistent watering is broccoli's biggest zero-input lever specifically -- since heat and drought stress are what actually trigger bolting, keeping the root zone evenly moist (mulch helps a lot here) does more to protect your harvest than any pest control does.