Brassica oleracea 'Romanesco'.
Probably the strangest and most mathematical vegetable in the garden. Native to the Lazio region around Rome — hence its name — documented in Italy since the 16th century, Romanesco intrigues everyone who sees it for the first time: not really broccoli, not entirely cauliflower, it's an intermediate variety of the same Brassica oleracea species that gave rise to both. Brilliant lime green, firm, sculpted into an architecture of spiralled points that defies perception. Cutting a Romanesco with a knife over the board is a small moment of visual stupor every single time.
The secret of its beauty rests on a remarkable geometric fact: each point is a small spiralled pyramid, itself composed of even smaller points following the same spiral, to infinity or nearly — a near-perfect example of a natural fractal. The spirals wind clockwise and counterclockwise following the Fibonacci sequence, the same growth pattern found in sunflowers, pine cones and nautilus shells. It is, literally, an edible math lesson. Fine, mild, lightly sweet and nutty flavour, much less sulphury than that of the classic cauliflower. Firmer texture too, which holds up better in cooking and keeps its crunch. Delicious roasted whole in the oven with olive oil and parmesan, in a gratin, in pickles, or raw in Italian-style pinzimonio — simply dipped in a well-salted lemony olive oil.
Grower's tip: Romanesco is demanding. It needs a long cool season (75 to 100 days), soil very rich in organic matter, regular watering without jolts, and above all — above all — it hates summer heat, which ruins head formation. In Québec, the winning strategy is to aim for a fall harvest: sow indoors in early June, transplant in early July, harvest in September-October when cool nights concentrate the sugars. Like all crucifers, susceptible to the cabbage worm; insect netting from transplanting on prevents decimation. Harvest when the head is well-formed but before it starts to relax — wait too long, and the beautiful fractal structure deforms.
- Open-pollinated. Biennial — flowering only occurs in the second year. Insect-pollinated; crosses with all other Brassica oleracea (broccoli, cabbage, kale, etc.) — isolate rigorously for seed saving.
- Height: 60 to 80 cm.
- Maturity: 75 to 100 days after transplant.
- Exposure: full sun in spring and fall; part shade accepted in summer.
- Very rich, deep, well-drained, slightly alkaline soil (pH 6.5-7.5). A very hungry plant — amend generously with mature compost. Space plants 45 to 60 cm apart.
- Indoor start 6 to 8 weeks before transplanting. For fall harvest in Québec, sow in early June and transplant in early July. Strict crop rotation with other crucifers (wait 3 to 4 years before putting another crucifer back).
