Feeding made simple

Q I have a lot of plants that have been growing in containers for some time. Some look needy, but there’s no way I can repot them all. How (and with what) can I feed them to bring the plants back to good health?

Susan Winstanley, Nantwich, Cheshire

A Growing shrubs, perennials and even trees in pots is rewarding, especially if you have a small garden or move around a lot. Yet, these long-lived plants will run out of nutrients within a few months and their roots gradually fill the containers, leaving little room for new ones to grow. Water often runs through pots stuffed with roots, leaving the plants thirsty. They are also more prone to extremes of summer heat and winter cold than roots in the ground.