Perennials are relatively easy to propagate. Most can simply be split into pieces in spring or autumn. But there are also some other methods of propagation that can be successful, depending on the type of plant.
Why would I divide perennials?
Dividing perennials is an excellent method of increasing your stocks
and also refreshes the plants, providing the opportunity to discard older, woody sections of the plant that are less productive.
When can I divide perennials?
Divide perennials either in spring or autumn, preferably during mild,
damp weather when the divisions
will settle in more quickly. Most
plants should be divided only every two to five years, allowing time for them to recover in between. Primulas (Primula vulgaris), however, should
be ruthlessly divided annually immediately after flowering. You can do this throughout the growing season except during periods of drought.
Be sure to keep the divisions well watered to make sure that they establish quickly.
How do I divide perennials?
Lift clumps with a fork or hand fork and shake the roots free of soil.
You should be able to pull apart some plants, such as hardy geraniums, into smaller sections in your hands. If the plant is congested, you may find it is easier to cut the plant with a sharp knife. For larger plants, drive two garden forks, held back to back, into the centre of the plant and use them to tease it into smaller sections. Sections from around the edge of
the plant are younger. Any from the centre that are straggly or woody can be discarded. You can divide the parent into several sections, but each should be well rooted.
Can any perennials be propagated by cuttings?
Certain perennials that do not divide easily can be increased by cuttings taken early in the season. Depending on the plant, you can take either stem-tip cuttings or basal cuttings.
If in doubt, try both methods.
When can I take stem-tip cuttings?
You can take the cuttings any time during the growing season. Many gardeners like to take cuttings of borderline hardy plants – such as penstemons – in autumn, to act
as an insurance against possible winter losses. You can overwinter the cuttings on a windowsill indoors, then harden them off the following year before planting out in mid- to late spring.
How do I take stem-tip cuttings?
Take cuttings around 8–12cm (3–5in) long from the tips of strongly growing shoots. They should not be flower-bearing. Trim the cutting below a node, then strip off the lower leaves
so that the lower third of the stem is bare. Fill pots with cuttings potting mix, then insert the cuttings. Tent the pots with clear plastic bags, held in place with rubber bands (or you can just fold the open end of the bag under the pot). Keep them in a warm position – but out of direct sun – until well rooted, usually two to six weeks.
Which perennials can be propagated by stem-cuttings?
- Helichrysum petiolare
- Lotus berthelotii
How do I take basal cuttings?
Some plants produce clusters of new shoots from the base in early spring, and it is possible to create new plants from this material early in the
season. Select strong-growing shoots from the outside of the crown and
cut them from the plant. There
should be a small piece of the old tissue (which may be slightly woody) at the base of each cutting. Trim off the lower leaves, then insert them
into pots of cuttings potting mix.
Tent the cuttings with a clear plastic bag. They should root within two
to six weeks. If you keep them growing strongly, they should flower the same year.
Which perennials are propagated by basal cuttings?
- Anthemis tinctoria
- Campanula latifolia
How do I take root cuttings?
Dig up the plants while they are dormant in winter and wash the
roots free of soil. Select roots of
pencil thickness and cut them from the plant. (Remove only a few roots
if you are intending to return the parent plant to the garden.) Cut the roots into lengths of about 5–10cm (2–4in). It is usually recommended
that you cut the top of each cutting straight across, and angle the cut at the base. This is to make sure you insert the cutting the right way up
in the potting mix. Fill a container with potting mix that is suitable
for cuttings and make holes for them with a dibber. Insert the cuttings vertically so that the flat upper cut is flush with the potting mix surface. Cover them with a fine layer of horticultural grit, then place them
in a cold frame. Leaves should
appear in spring, when you can pot them up individually.
Which perennials can be propagated from root cuttings?
- Papaver orientale
Can I root cuttings in water?
Many soft-stemmed plants can be rooted in water – try osteospermums, penstemons, fuchsias, mints and tradescantias. Fill jars with tap water, then take cuttings around 8cm (3in) long from the plant. Strip off the lower leaves so there is a clear length of stem at the base. To suspend the cuttings in the water, either place two cocktail sticks (toothpicks) over the jar to support the lower leaves or cut a piece of chicken wire to sit over the jar and hold the cuttings in place. Stand the jars on a windowsill, but shade them from full sun. Change the water every few days. They should root in two to three weeks. Roots produced in water may be brittle.
Taking root cuttings 1: Dig up the plant in winter and wash the roots clean of soil. Cut off roots of pencil thickness.
Taking root cuttings 2: Cut the root into sections. Trim them straight across the top, angled at the base.
Taking root cuttings 3: Insert them upright in pots of cuttings potting mix so that the straight upper cut is flush with
Taking stem-tip cuttings 1: Take cuttings of healthy looking non-flowering shoots at any time during the growing season. Take several at different intervals.
Taking stem-tip cuttings 2: Trim off the basal leaves, then insert the stems in pots filled with cuttings potting mix.
Taking stem-tip cuttings 3: Cut a clear plastic drinks
bottle in half and use this to create
a mini-propagator for the cuttings.