Dividing perennials is a necessary and rewarding autumn chore. Dividing plants such as Hostas, Astilbes and Pelargoniums increases your inventory, tidies up the garden, and restores established perennials to tip top shape for next year.

A perennial is any soft bodied plant that survives for more that one growing season. It becomes dormant during the winter and bounces back to life the following spring.

To divide and transplant successfully it's wise to follow a few simple rules. First, get organised. You will need a shovel, bone meal, some compost, and a large serrated knife.

Perennials usually need to be divided every three years. If a plant looks like it has outgrown its spot, it's definitely time. Give the perennial a good watering - this will help to loosen the soil as well as ease the shock of division. If it is a tall perennial trim the height back to a maximum of 10". Next start to dig deeply (a full shovel length should do) around the outermost edge of the plant. The root ball will be visible. Gently dig and lift the plant completely out of the ground - and don't worry - it hurts you more than it does the plant.

As a rule of thumb, a perennial can be divided the number of times as years it has been in the ground. For example, if it has been in place for four years it should yield four healthy plants.

Assume the rootball is a pie and slice it with a strong 12" stainless steel serrated knife into quarters, thirds, or even eighths. Start from the top of the pie and make a clean cut right through. When all the cuts are complete gently separate all the pieces.

The pieces may look small but they will survive and flourish. For each new plant dig a hole, add a handful of bone meal, water well and top dress with well rotted compost for winter protection.

Some easy candidates for division include Hostas, Astilbes, Echinacea, Asters, Daylilies, Coreopsis, Bee Balm, Sweet William, and Yarrow.