Cichorium intybus.

Radicchio is a chicory — exactly the same species as the blue-flowered wild chicory of the roadside and as Belgian endive. Northern Italy turned it into an art. The Veneto has several recognized radicchios, each tied to its town, and Rosso di Verona is the one with a round, tight head, of a deep garnet red shot through with white veins. Its bitterness isn't a flaw to correct, it's the product: it comes from intybin, a bitter compound Italian cooking has always used as a counterpoint to fat and sugar.

And that's where the plant gets interesting for a Québec gardener: cold is its ally, not its enemy. Sown in spring, radicchio stays green, loose and hopelessly bitter. Sown in June or July for a fall harvest, it crosses the summer as an open rosette, then, when nights cool and especially after the first light frosts, it forms its head, takes on its red colour and loses a good part of its bitterness. A radicchio harvested in October after two frosty nights bears no resemblance to one from the same plant in August.

In the kitchen: grilled in quarters on the BBQ or in a pan until the edges caramelize, then dressed with balsamic vinegar and olive oil; melted into a risotto al radicchio, one of the great dishes of the Veneto; raw in a salad with walnuts, pears and gorgonzola, the classic triad that balances bitterness with fat and sugar; or in leaves rolled around a piece of pancetta and baked.

Grower's tip: if your radicchio has never made a head, it's almost always a question of calendar, not technique. Sow in late June or July, never in spring. In September, when the rosette is well developed but still open, some gardeners cut the foliage back to 5 cm above the crown: the regrowth then forms a much tighter head. And above all, don't rush the harvest. Let two or three light frosts go by.

• Open-pollinated. Italian heirloom variety from the Verona region. Biennial, flowering in the second year.
• Grows in ~80 days.
• Exposure: full sun.
• Ordinary to rich, well-drained, cool soil. Space plants 25 to 30 cm apart.
• Sow late June to July in Québec for a fall harvest. Spring sowing gives bitter plants that don't head up.
• Harvest after the first light frosts: cold reddens the head and softens the bitterness.