With my perennials I am always making more of them either by division or cuttings. Most require cutting back to make a fuller plant, and all those cuttings are easily rooted for most perennials. I have built up good inventories of Altromerias and Daylilies through divisions. Al

Thanks for information regards cuttings/divisions. But to clarify perennials are very young plants so they currently are 4L containers. At this stage I don't think they are mature enough to take cuttings/divisions - I thought you divide them once 2-3 years old. So I was wanted to replant them into a large container but I am unsure whether I can do this now while they are in active growth and flowering or wait til either autun or next spring.

To determine if my perennials need potting up to a larger sized container, I knock them out of their pots and take a look at the roots. If they are starting to circle the inside of the pot, I will carefully pot to larger size. With most mixes the roots will hold the mix together and not be disturbed when potting up. Most plants will take this move anytime, without causing a stress. If you are using a gritty mix it will fall off the roots, and I would wait for the plants dormancy when root disturbance is better tolerated. Al