Seed companies offer so many salad leaf varieties these days and the good news is that you can be picking them all summer long and beyond if you sow little and often. One of the simplest ways to grow salad leaves is in pots or troughs, making sowings every couple of weeks from March through to the end of August. Fill containers with multipurpose compost, sow seeds thinly, give a light covering of compost and water in.
There are lots of options but cut and come again varieties mean that you can maximise what you grow with three or more cuttings. If you want variety you can buy packets of mixed salad leaf seeds, or buy individual varieties and grow separately.