That’s because established perennials can need dividing after a few years because they’ve grown so big, developing gaps at their centres, and are congesting other plants. Or you might want to move them simply because a bed or border needs a refresh.
Lifting and dividing plants is relatively straightforward with the right tools and will give your muscles a good workout into the bargain. September is a good time to do this as the soil is still warm.
Firstly, identify the new positions for your divided plants and add some organic matter to give them a good start.
Some plants, like hostas, can be teased apart with your hands, but for others you will need to use a fork to gently dig out and split the clump and then put the divided sections on some sheeting.
For well-embedded large clumps you will need to use the double fork technique. Here two forks are placed back-to-back in the centre of the clump and then pushed to prise the plant apart. (Push on the metal sections to avoid breaking the wooden handles).
Transport them to their new spots, bed them in, give them a good water regularly and it shouldn’t be long before their roots take to their new home.
Dividing perennials is a simple way to boost the number of plants in your garden for free. It’s also a way to correct planting mistakes, for example when a flower's colour or height clashes with plants around it.
This job has therapeutic qualities too. You’ll mentally lose yourself in the task, it’ll get your creative juices flowing as you work out where to place divided plants, and there’ll be a sense of gratification when you see the results.
A word of caution to finish. Some perennials don’t like being moved at all, so always research your specific perennial before going to work on it.