You can start Cardoons off one seed to a single pot indoors from as early as February or sow direct outside from April to June once the soil has warmed up. They need a final spacing of about 75-90cm
In October through to mid November you need to blanch the Cardoons by wrapping layers of cardboard or sacking around the stems and tying it up with string leaving the fronds of leaves poking out of the top. This helps to make the stems tender and removes the bitterness before harvesting. 3-4 weeks of blanching is usually enough and then you can cut individual stems for eating or slice the whole plant at its base like a monster head of celery leaving the root to re-sprout in the spring.