How to Propagate Viburnum from Cuttings, Layering and Seed

Which method to use, and when

Viburnums root readily from cuttings, and the only real decision is which kind of wood to take and therefore which season to work in. Softwood cuttings, taken from soft new growth in early summer, root fastest but wilt fastest and need a closed environment. Semi-ripe cuttings, taken in late summer from growth that has begun to firm at the base while the tip is still soft, are slower but survive neglect far better and are the right choice for a first attempt.

Hardwood cuttings, taken from fully dormant deciduous wood in late autumn or winter, work for some deciduous types and need almost no attention through the winter, but the success rate is lower and you wait until the following summer to know whether it worked. Layering works for everything with a low flexible stem and needs no propagator, no misting and no attention beyond patience.

Seed is possible but slow and unpredictable. Viburnum seed commonly has double dormancy, meaning it needs a warm period to develop a root and then a cold period before the shoot appears, so germination often takes eighteen months or more and the seedlings will not match the parent. Use seed only if you want a batch of variable plants, not a copy of the one you have.

Semi-ripe cuttings, step by step

This is the method to learn first. The wood is at its most cooperative in late summer: the base has firmed enough to resist rotting, the tip is still growing enough to root, and the weather is warm without being extreme. Take more cuttings than you need, since they cost nothing and the loss rate is never zero.

1. Take the material early in the day Cut shoots four to six inches (10 to 15 cm) long from healthy non-flowering side growth, in the morning while they are full of water. Put them straight into a plastic bag with a splash of water and work in the shade.
2. Trim to a node and reduce the leaves Cut cleanly just below a leaf joint, remove the leaves from the lower half of the cutting, and halve the remaining leaves across if they are large. Leaf area drives water loss; leaving too much foliage is the commonest reason cuttings collapse.
3. Wound the base and dip it Scrape a thin sliver of bark from one side of the base for about half an inch (12 mm), then dip in rooting hormone. The wound exposes the tissue that produces roots and noticeably improves the strike rate on woody shrubs.
4. Insert into a gritty free-draining mix Use equal parts of a peat-free potting mix and sharp grit or perlite. Push cuttings in to about a third of their length around the edge of a pot, firm gently, and water once to settle them.
5. Keep humid, shaded and out of direct sun Cover with a clear bag held clear of the leaves, or use a propagator, and keep in bright shade at around 65 to 70F (18 to 21C). Direct sun inside a bag cooks cuttings in an afternoon.
6. Check for roots by resistance, not by digging After six weeks, tug one cutting very gently. Resistance means roots. Once rooted, ventilate gradually over a fortnight before removing the cover, then pot up individually and overwinter somewhere frost-free.

Layering: the method that cannot really fail

Layering exploits the fact that a viburnum stem in contact with soil will root where it touches, while still being fed by the parent plant. Because the stem is never detached until it has its own roots, there is no wilting stage and no propagator, which is why it succeeds when everything else has failed.

Choose a young flexible stem low on the plant that can be bent to ground level without snapping. About a foot (30 cm) back from the tip, scrape a shallow wound on the underside of the stem, then bend that point into a shallow depression in the soil, peg it down firmly with a wire staple or a stone, and cover it with two inches (5 cm) of soil. Tie the tip to a short cane so it stands upright out of the soil.

Then leave it. Keep the spot from drying out completely in summer, and check the following autumn by scraping away the soil. Once there is a decent set of roots, sever the layer from the parent on the parent side of the roots, leave it in place for a few more weeks to adjust, then lift and plant it. Some layers need a second year; there is no penalty for waiting.

Label every cutting batch and layer with the date taken and the parent plant, and write down the strike rate when you pot on. Knowing that late summer gave you eight out of ten and early summer gave you three out of ten is what makes the next round better.

Growing on, and what to expect

Rooted cuttings are fragile for their first winter. Keep them in a cold frame, unheated greenhouse or sheltered spot against a wall, protected from hard frost and from waterlogging, which kills more young viburnums over winter than cold does. Do not feed until growth restarts in spring, and then only lightly.

Pot up into a slightly larger container as soon as roots reach the sides, and pinch the growing tip once in the first spring to force branching from low down. A young viburnum that is allowed to run up as a single stem makes an awkward, bare-legged shrub that is difficult to correct later.

Plant out into the garden after two growing seasons, when the plant is a foot or more (30 cm plus) tall with several stems. Expect a home-propagated viburnum to take three to five years from cutting to first proper flowering, since flower buds only form on wood that has had a full season to ripen and a young plant is spending everything it has on frame and roots.