Lettuces in the Cold Frame (gouache style)

Lettuce belongs to the daisy family and is descended from wild prickly lettuce. Four main types are grown: soft butterheads, tall crisp cos lettuces, crunchy crispheads and loose-leaf kinds that can be cut and left to regrow. Red-leaved varieties such as 'Lollo Rosso' and 'Marvel of Four Seasons' add colour, while 'Winter Density' and 'Arctic King' are among those bred to stand cooler weather. It's one of the quickest leaf crops to grow.

Sow little and often outdoors from March to August, every couple of weeks, so you don't end up with a glut. Seed can be slow to germinate in hot weather, so summer sowings are best made in the cool of the evening. A cold frame comes into its own at both ends of the year: hardening off seedlings in April and May, then sheltering winter lettuces sown in August and September. On warm days, prop the lid open and close it again at night. Keep a watch for slugs.

Rows of green and red lettuces fill a wooden cold frame here, with its lid propped open to let in air. The open lid tells you it's a mild day, and the neat rows show the frame doing its job of keeping salad leaves growing beyond the main season.