This old Italian heirloom radicchio grows in an upright, columnar shape like a little urn. Pull away the lavish wrapper leaves to reveal a stunning red and white, blanched, sweet centre. Treviso is a cold hardy radicchio. Treviso chicory seeds produce plants that are beautiful in the garden. Try it grilled on the barbecue and drizzled with olive oil and balsamic vinegar. Or create a hot oil salad dressing and apply just before serving. Radicchio will stand up to heat, and this heat brings out the sweetness and improves the flavour. The long stems (petioles) of this radicchio are crunchy and succulent.
Matures in 85 days. (Open-pollinated seeds)
The chicory family includes the food plants endive and radicchio, which range widely in shape, and in flavour from bitter to sweet. All varieties become sweeter, and lose much of their bitterness, when cooked. Try a hot oil salad dressing over endive, or a barbecued head of radicchio. Continue reading below for tips on how to grow endive and radicchio from seed.
Cichorium endiva (endive) & C. intybus (radicchio)
Endive is easy.
Radicchio is moderately difficult.
Belgian endive (witloof) is downright challenging – but worth the effort.
Season & Zone
Season: Cool season
Sow after the last frost date and again in mid-summer to take advantage of the fall growing season. Optimal soil temperature: 10-22°C (50-72°F). Seeds sprout in 2-15 days, depending on conditions. In hot weather plants may go to seed quickly, so have new plantings ready to go.
Either direct seed or start indoors and transplant. Sow seeds 5mm (¼”) deep, and thin or transplant to allow 30-45cm (12-18″) between plants in rows 30-45cm (12-18″) apart.
Days to Maturity
From direct sowing.
Ideal pH: 6.0-6.5. Enrich soil with compost and add ¼ cup balanced organic fertilizer into the soil beneath each transplant. Rapid, continuous growth is essential for good yields and high quality. Regular watering is essential. Fall plantings can be protected from rain by putting a cloche over them. Endive heads can be blanched to reduce bitterness by placing a cardboard or plastic disc on top. Radicchio requires a good supply of phosphorus and potassium, but will not head and may bolt if there is too much nitrogen available. Days to maturity shown are from date of direct sowing. If transplanting, subtract 10-15 days.
Use as a cut and come again crop or let the heads develop and cut at ground level. Many will grow back.
In optimal conditions at least 65% of seeds will germinate. Usual seed life: 3 years. Per 100′ row: 140 seeds, per acre: 40.6M seeds.
Diseases & Pests
Aphids – Water can be used to remove aphids from plants. Wash the plant off with water occasionally as needed early in the day.
Moulds and rot from heavy rains can be prevented by growing under cover. Tip burn is a calcium deficiency within the plant that can be caused by an imbalance with over nutrients. Make sure to add lime to the soil, do not over-fertilize, and harvest just before full maturity.