Plant Propagation Techniques – Dividing Plants
There are several different plant propagation techniques and this article will cover how to propagate plants using the division method.
Dividing Plants – Young Perennials
Young, tufted perennials with fibrous roots, such as Helianthus, Michaelmas daisies (Aster) and Rudbeckia, are easily divided. Once lifted, they can be pulled apart by hand or with a small fork — each section should contain healthy roots and strong growth buds.
Cut off any dead roots and leaves with a sharp knife Replant the divisions at once in their permanent positions. Tiny divisions can be planted in a nursery bed in an out of the way corner of the garden or in individual pots until the following autumn, when they can be planted out in their permanent positions.
Dividing Plants – Mature Perennials
Large, overgrown fibrous-rooted perennials, such as heleniums and phlox, are often difficult to divide —the crowns and shoots form a solid mass. Begin by lifting the clump — or part of it — as before. Having lifted the clump, push the prongs of two strong garden forks, back to back, into the centre of the clump.
Most garden forks have curved prongs, so when put back to back you have a useful lever device. If you possess only one fork, borrow another from a friend or improvise by inserting a couple of stakes through the clump and into thebelow against which you can lever with one fork.
Lever the clump apart first by forcing the handles of the forks together — thus forcing the tips of the prongs apart and so separating the lower roots. Then force the handles of the forks away from each other. Repeat until the clump splits in half. Divide each half once again.
With a sharp knife, cut away and discard the woody part of each portion which came from the centre of the original clump. Separate the remainder into healthy pieces, each containing about six buds or shoots. Also remove dead or rotten roots, then plant out. Water them if the soil is dry.
Woody-crowned perennials, such as Baptisia and Rheum, can’t be split with garden forks. Instead, cut through the crowns with a sharp knife, so that each severed portion has both root and growth buds. Replant the divisions immediately.
Fleshy-rooted plants, such as Agapanthus and Hosta, are best divided by hand in the same way as young perennials — it is easier to separate the brittle roots without damaging them than if you use forks.
Dividing Plants – Tuberous Plants
The method of dividing tuberous-rooted plants varies according to the type of tuber.
Dig up the clump as before and gently tease away the soil — do not damage the tubers. If the soil sticks to the tubers, immerse them in a bowl of water — the growth buds must be clearly visible.
Root tubers, such as those of day(Hemerocallis) and herbaceous peonies (Paeonia), have growth buds in the crown where the tubers join together. Using a sharp knife, slice downwards through the crown to divide the plant into several pieces, complete with tubers and growth buds. Plant the divisions at once.
In general, sections of single tubers with only one growth bud take longer to produce good-sized plants than those with three or four tubers and buds.
Herbaceous peonies often resent having their roots disturbed, so recovery may take a season or more. To give peonies less of a shock, divide them in autumn or early spring when the weather is not too harsh and while the tubers are dormant.
Small claw-like tubers, such as those of Anemone and Liatris, can be pulled apart by hand. Large tubers, however, may need to be cut into pieces with a knife Make sure each piece has a strong growth bud before planting.
Dividing Plants – Rhizomatous Plants
Rhizomatous-rooted plants, such as Bergenia, Monarda, Physalis and Polygonatum, are quite easily lifted — their rootstocks, which are really swollen underground stems, grow just below the surface of the soil.
Lift the rootstock in early spring just as new growth buds are beginning to emerge. Tease away the soil to expose the old main rhizome together with the younger underground stems coming from it.
Select side growths which have two or three strong growth buds or vigorous young shoots, as well as healthy roots. Any 5-7.5cm (2-3in) long side shoot is suitable for replanting. Remove these growths with a sharp knife, making a clean cut through rhizome and roots.
Discard the old rhizome and trim the new growths back, cutting to just below a cluster of healthy fibrous roots. Cut off any stump and rotten parts from the selected pieces. Also remove all dead leaves and leaf stalks.
Plant the sections at once. Position vertically in the soil with the root cluster downwards and fairly deep — the rhizome must be well anchored in the soil and at about the same depth as the original plant. Label the plants carefully and water in.
Dividing Plants – Shrubs
Many shrubs produce shoots from underground buds — including Ceratostigma, Clerodendrum, Kerria, Romneya, Rubus and Ruscus. The buried bases of the shoots produce their own individual roots. Such shrubs can be divided in the same way as woody.
Lift the shrub in spring — though any time between mid autumn and mid spring may be successful. Using secateurs or a small pruning saw, cut the woody base into several equal-sized pieces, each wih plenty oproduceand top growth attached. Replant the divisions at once.
Many trees and shrubs also produce shoots from below ground — these are called suckers. They include Ailanthus,, , Philadephus, Rhus, Rubus, and .
Suckers appearing from the base of grafted shrubs are not suitable for use as propagation stock — they may be too vigorous and will not have the same characteristics as the parent. Suckers from grafted shrubs should always be removed as soon as they appear.
Remove soil from the base of the sucker any time between mid autumn and early spring. If the sucker has roots it is suitable for lifting. Using secateurs, cut the sucker close to its point of origin with the stem or root.
Plant well-rooted suckers in a permanent site in the garden. Poorly rooted suckers should be planted in a nursery bed and grown on for a year or so.
Other plant propagation techniques include: