Root cuttings

This method involves taking a section of root and planting it, from which a new plant will grow. Root cuttings are generally taken when the plant is dormant, between mid autumn and late winter.

It should be noted that if a root cutting is taken from a variegated plant, the new plant will not have the variegation (ie the leaves will be plain coloured).

The plant from which the cutting is to be taken should be lifted (from its pot or the ground) and the roots washed free of soil/compost. Strong roots of a medium thickness (the actual thickness will depend on the plant), with no signs of damage or disease, should be selected and cut off as near as possible to the top of the root. Cut each piece with a straight cut at the top, so you know which way up they were on the plant.

Don’t remove more than a third of the roots if you want to retain the parent plant. When you re-plant the parent, remove an equivalent proportion of its top growth – otherwise the plant will not have a sufficiently large root system to support the original amount of foliage.

Cut each of the removed roots into sections which are 5 to 13cm long – the thinner the cutting, the longer the section should be. Continue to make straight cuts across the top of each cutting, and slanting cuts across the bottom, to ensure you plant them the same way up as they were on the plant.

Place the cuttings in pots of cutting compost, which have been watered well and allowed to drain. You can treat each cutting with a fungicide before planting it, if wished. Use a dibber to make a hole in the compost then stick a cutting in, so the straight cut across the top of the cutting is level with the surface of the compost. You can put more than one cutting in each pot, each in its own hole. If your cuttings are on the thin side, you can lay them horizontally along cutting compost in a tray, about 2.5cm apart, and cover them with 5mm of compost.

Cover the surface of the compost with a layer of coarse sand or grit which is about 1cm deep – this will provide a well drained layer beneath the first, very soft, top growth, which should reduce the risk of rots or fungal infections.

Cuttings from plants which are fully hardy, or frost hardy (surviving temperatures below 0ºC) can be placed in a cold frame. In extremely cold weather, additional protection may be required to stop the compost freezing completely. Cuttings from more tender plants should be kept at a minimum of 7-10ºC, in a sheltered place (generally this will require a heated glasshouse or an indoor windowsill). Bottom heat may encourage slow rooting plants to develop more quickly.

Keep watering to a minimum, just enough to stop the compost drying out, until the cuttings show sign of growth, to minimise the risk of rotting. Top growth will generally appear in the spring. The cuttings should be potted on when they have good root system development. Carefully lever a cutting up (eg with a widger) so you can judge whether the root system is well developed. Pot on into individual pots filled with potting compost, water well and grow on until they are big enough to plant out.