I was going to make this a one off article on autumn propagation but I decided that it was becoming too long, and too complicated and that nobody would bother to read it! So my intention now (so long as the editor approves), is to produce propagation notes each month with a few suggestions as to which plants to try. On the basis that we all have to start somewhere, I make no apology for the fact that some of this will be very basic to some of you. More challenging suggestions will follow!
Just a few general observations before we start:- Propagation falls into two main types – Seed and Vegetative. There are pros and cons for each, but put simply
1) if you propagate vegetatively, the offspring will be genetically identical to the parent plant. If you use seeds, the progeny will be variable (except in the case of commercially produced seed where pollination has been controlled).
2) Generally vegetative propagation results in smaller numbers of progeny
3) Some plants, particularly hybrids, do not produce viable seed. Others will not produce seed under UK climatic conditions.
4) Some plants will only propagate by seed. These include annuals but also some perennial plants and trees.
Propagation tasks for October
The simplest form of vegetative propagation suitable for herbaceous perennials
which bulk up by gradually forming bigger and bigger clumps. Plants of this type should
be divided about every three years to maintain their vigour. Lift the entire clump and
gently tease apart. Each piece should come away with some root attached – for tougher
plants you will need to use a knife. If you are just replanting, there is no need to break
up into individual pieces. Simply split it into a few new clumps taken from the outside of
the old one. Throw the centre (oldest) part on the compost heap. If you want to produce
a lot of plants, then you can take individual pieces and pot them up into a low nutrient
compost. This is important at this time of year as the plants will not make much growth
before next year and excess nutrients will encourage bacterial growth. They may also
encourage soft growth before winter sets in, which will make the plants more
susceptible to frost damage. Feeding can begin in spring next year. The plants can be
left outside without protection. Plants which can be propagated in this way in the
autumn are most of the earlier flowering perennials, eg Alchemilla mollis, Cephalaria
gigantea, hardy geraniums, violets, and lots more!
- Softwood Cuttings
It’s getting a bit late for these now and I’ll say more about them at a later date.
However, if you have plants that are not reliably hardy, you might consider taking some
cuttings and overwintering them with protection (frost free), just in case the parent plant
doesn’t survive. Penstemons and Osteospermum are obvious candidates from the
garden borders, and Pelargoniums from your pot plants. Choose non-flowering shoots from the current season’s growth. Using the upper section of the shoot, reduce the length to about 8cm, cutting immediately below a node (the point where the leaves come out of the stem). Trim off the lower leaves so that you have a clean piece of stem to insert into the compost. Use a low nutrient compost mixed 50:50 with horticultural grit (or perlite if you prefer). Depending on numbers, you
can use pots or seed trays. Once the cuttings are inserted, water gently and put in a propagator. The main purpose of this is to stop the cuttings from drying out. If you have a heated one, that’s perfect, but it’s not essential. Heat will simply speed things up a bit and also makes things a bit more tricky when it comes to hardening off the rooted cuttings.
It’s worth noting that Pelargoniums don’t like a damp atmosphere and I usually leave
them uncovered. The old gardeners used to take the cuttings and leave them out
overnight on the potting shed bench before completing the process! Whatever you
decide, I would advise that you don’t keep them in with other cuttings that like a bit more
By late January you should have some rooted cuttings that you can pot up and
gradually harden off ready for planting out in May.