Have you seen those little pots of herbs in the supermarkets? Aldi are 59p then it goes through the roof..... Basically, they are immature plants, forced in inadequate space. Just as an experiment, I bought some cheap (Poundland ) troughs and a big bag of potting compost. All you do is dunk the rootball in water to loosen off the compost, gently tease apart the individual plants, then pot on in the troughs, preferably inside at first. It's worked well with basil and parsley, got 2 months supply from each pot, and also the "Living lettuce" in places like LIDL, only takes a couple of weeks to bring on a couple of months supply of herbs and lettuce.