Propagation by Root Cutting

1. Lift the plant you want to propagate when it is dormant.
2. Carefully wash the roots.
3. Select a number of roots of pencil thickness; they may be smaller for some thin-rooted plants such as phlox, Campanula spp. or drumstick primrose (Primula denticulate).
4. Using a sharp knife, cut the selected roots straight across, close to the crown.
5. Trim off the side roots and cut the remaining root into lengths of approximately 5-10 cm (2-4 in). Make sure you make a straight cut at the upper end of each section and an angled cut at the base. Cut thin roots into slightly longer sections; about 7-12 cm (3-5 in).
6. Place the cuttings upright in a pot filled with moist cutting compost so that the straight end is level with the soil surface and add a top-dressing of grit or sharp sand. Thin-rooted cuttings should be laid horizontally flat on compost in a seed tray and covered lightly with more compost.
7. Place the cuttings in a cold frame or cold greenhouse for the winter to give them protection until they have rooted. Keep them moist.
8. When shoots appear from the top of the cuttings the following spring, pot them up them to individual containers filled with loam-based potting compost. They may be transplanted to their final positions the following autumn.

Taking Cuttings

Cuttings should be at least 2.5cm (1 in) long; the longer the root, the more food it will have stored. Roots that are to be propagated in a cold frame will take longer to grow than greenhouse cuttings, and so will require more food, so you will need to make these cuttings at least 5 cm (2 in) long. Plants such as lilac (Syringia) that can be propagated in open ground will need even greater amounts of food reserves, and should be 10-15 cm (4-6 in) long. As thin roots contain less food reserves, cut them slightly longer than the recommendations for thick roots.

Roots may be inserted into the growing medium so that their proximal ends (the ends that were nearest the crown of the plant) are flush with the soil surface; however, plants with thinner roots, such as phlox should be laid on the compost horizontally.

Roots are produced from the end farthest away from the crown of the plant (the distal end) and so great care must be taken to ensure that the cutting is inserted into the rooting medium the right way up.

To avoid confusion, make the cut nearest the crown straight (the proximal end), and then cut the root end (the distal end) at an angle.