If your soil is healthy and reasonably rich in compost, and you are growing varieties such as Chartwell, Freckles, Maravilla di Verano etc (not Salad Bowl!), and you pick carefully (not difficult with a bit of practice), then ten weeks picking is possible, or longer.
Allow five weeks in summer from sow to first pick, so you could make a second sowing four or five weeks from now, by mid July, to keep you in lettuce until October.
