New plants from old, part 2

If you think propagation is difficult, you haven’t tried division. It’s such a complete doddle the only conceivable way you might stuff it up is by dividing something at the wrong time of the year, or by replanting into extremely unfavourable soil. As a basic rule, plants divide best in the cooler seasons when they have time to establish new roots without the pressure of summer heat. Evergreen plants are best divided in autumn, deciduous plants in winter or early spring.

The technique works with any plant that forms a central crown or clump, and those that spread via underground rhizomes. Herbaceous perennials such as echinacea, catmint, rhubarb and daylily are examples of the former. Canna lily, agapanthus, and clivia are examples of the latter.

In either case, simply dig up the plant at the appropriate time of the year, and cut it up into pieces with an old knife or in the case of aggies, a hatchet or sharp spade. As long as there is some root attached to the plant, you’ll generally be fine. Once you’ve made your divisions, either pot them up to grow on, or plant them out as soon as possible into prepared soil. An initial drink with sea weed extract will help them settle in, and depending on the weather, you may need to water the new plants regularly to get them properly established. Simple, right?

Most woody plants such as shrubs and trees can be grown from cuttings, and in some cases it’s as easy as snipping off a branch tip, poking it into the ground and keeping it moist for a few weeks until the cutting develops new roots. You’ll have a higher strike rate, however, if you take a more systematic approach to the technique.

Cuttings basically come in three forms – hardwood, softwood, and semi-hardwood. Hardwood cuttings are taken from deciduous trees and shrubs in winter, softwood cuttings are taken from shrubs in spring, and semi-hardwood cuttings are taken in early summer as spring growth starts to harden off. Space precludes me from going into great detail about each method here, but a book I highly recommend is The RHS guide Propagating Plants by Alan Toogood.

In my experience most cuttings strike best in a fairly loose, airy propagating mix. I blend my own by mixing two parts potting mix designed especially for cuttings, to one part pearlite. Every technique is slightly different but I prepare most cuttings by trimming them to length, stripping off the lower leaves and in most cases, slicing off a sliver of bark at the base to encourage rooting.

A dip in some hormone powder or liquid also helps with root formation. I place small cuttings in clear plastic propagating units (available at nurseries or online) to prevent them drying out too quickly, and then place the units in my greenhouse, which is covered with 50 percent shadecloth. Dappled light beneath a large tree will work just as well, but avoid direct sunlight or your cuttings will cook. Roots will form in about a month for softwood cuttings, at which time individual plants can be potted up and grown on, or planted out into a prepared garden bed.

If I had to choose a favourite propagation technique it would be grafting. The method works by taking a cutting, known as a scion, and splicing to a receiving plant known as a rootstock. Various techniques are used to splice the two plants together, but the main methods I use are whip and tongue grafts in late winter with deciduous plants (such as apples), and chip budding in early summer with evergreen plants (such as citrus).

If you’re keen to have a go, I’d recommend a few things. First consult a good book, such as that mentioned above, or check out some of the excellent grafting tutorials on Youtube. Second, use a very sharp knife, ideally one designed for grafting. It seems counter-intuitive, but the sharper the knife the less likely you are to take off a finger while attempting a whip and tongue. Third, practice on prunings to learn the various techniques. And fourth, try grafting some new varieties onto an existing tree in the garden. This avoids having to grow or source rootstock, and produces a multigrafted tree that will bear more than one variety of fruit. As long as you graft like to like (apples to apples, pears to pears for example) you shouldn’t go far wrong.

My final piece of advice, and a rule I recommend everyone tries to live by, is get stuck in and have a go. You’ve got plenty to gain, nothing to lose, and in the process, might discover the unique rewards to be gained by starting new plants from old. Propagation is a lifeskill worth learning.

First published by the Toowoomba Chronicle 19th January 2013.