Claire Austin explains how to multiply your perennials
Try your hand at root cuttings to get more plants for free
Winter’s a great time to create new plants from old ones. Perennials tend to be easy to multiply. Many germinate readily from seed but plants raised through hybridisation won’t resemble the original. The names of hybridised plants are surrounded by inverted commas, such as geranium ‘Orion’. Although their seedling offspring might look similar to the parent plant, they’ll never be identical.
The most reliable way to multiply perennials is to divide them by lifting the plant from the soil, usually between late October and February, when the leaves have died down, and then splitting it into smaller pieces. New plants created in this way will look exactly like the old one. But not all perennials can be divided. If leaves grow from a tight centre, such as eryngium (sea holly), echinops (globe thistle), bergenia (elephant’s ears) and anchusa (alkanet), there’ll be nothing to divide. Sometimes leafy sideshoots can be taken, but the best way to propagate them is by using a method called root cutting. It can also be used to propagate plants that suffer from debilitating diseases. Phloxes often fall prey to nematodes (previously called eelworm), which leave nodules on the roots. By using only healthy roots, root cuttings can create strong plants. Similarly, oriental poppies ( Papaver orientale) have declined in recent years due to a fungal disease, but stronger plants can be created by multiplying those with healthy, strong roots. Take root cuttings when the plant is totally dormant, between November and January. Roots can vary in size – those of anchusa and papaver are thick and go deep into the soil, whereas phlox and Japanese anemones have slender roots that travel through the soil and any fragments left behind naturally regenerate.
Lift the plant from the ground and slice off long lengths of root. Make sure the bottom of the root is cut at an angle so you know which end is which. Lay the root flat on a cutting board and slice into sections, about the length of a finger, using a sharp, thinly-bladed knife such as a scalpel. Place the sections of root flat in a seed tray of compost and cover with soil with the tops just showing. Make sure the roots are tucked in nicely and water lightly.
I then abandon them in a cold greenhouse throughout winter. Don’t be tempted to disturb them because the roots will start to grow before the tops. Keep pots reasonably dry and in spring you should see bits of green springing up from the compost.