|
[Front Page] [Features] [Departments] [Society Home] [Subscribe]
Successful Propagation: Making the Right Choices
Alan Hodge
Sooner or later, most of us who become keen on growing Australian native plants get the urge to try and propagate our own. But why? What gives us this urge? Perhaps we have an especially favourite plant, and we want to grow more like it. Maybe, like me, you are parsimonious by nature, and reckon you can create something for free. Sometimes, you want more of a plant that you just can't find in the nurseries. And perhaps, like me you get bitten by a kind of creative bug, and end up getting more fun out of experimenting with propagation than with actually growing on the seedling you have successfully produced.
If you are just starting out, you can't do better than study our own Angus Stewart's authoritative "Let's Propagate - a Propagation Manual for Australia" which has appeal for the professional and the layman alike; it is full of down to earth advice and explains many of the "tricks" that good plant propagators use. This manual of some 240 pages covers all aspects of propagation, from seed, from cuttings, by layering, using smoke-induced germination, optimum potting mixes and environmental control - in short, the lot.
In this short article, I will limit this vast field to some aspects of vegetative propagation from cuttings, and look at some of the simple "tricks" that our experienced propagators use.
When?
The first choice you make is when to take your cutting. Stewart will give you 23 pages of Australian plants, listed alphabetically with details of the best time of year to take cuttings. One learns from experience the optimum time for taking successful cuttings. For example, you can propagate Brachyscome all year round, but I find that new growth taken from August to November almost guarantees success.
The time of day is important. Early morning seems to be best. After recent rains, when the shrub or tree has taken up moisture will help. And it seems best after flowering as a general rule, when the plant is not putting its energy into forming buds and flowers. It goes without saying that the shrub or tree should be healthy and disease-free.
The cutting
The next series of choices concerns the cutting itself. You will want to sterilize your secateurs, by dipping in a weak bleach solution. The secateurs need to be sharp enough to give a clean cut; anvil-type secateurs are not suitable. Cut the stem at an angle just below a node, and place the cut stem in water immediately. The best type of cutting material seems to be strong young growth that is starting to firm, preferably taken from lower down rather than at the tip. (You can encourage such growth on your shrubs by regular pruning).
The next choice is preparation of the cutting. The lower 1/3 of leaves are cut away (or stripped if the plant is soft enough). Any flowers or buds are removed. The soft top stems and leaves are cut away cleanly just above a node. The bark at the base of firmer semi-hardwood cuttings can be shaved away with a blade to aid root formation. The cutting can be dipped in hormone rooting powder or gel. (APS member Pat Parish swears by honey instead of hormone; it has fungicidal properties, and supplies sugars that can be drawn on for nutrient).
The mix
Different plants require different mixes. Only by your own experiments will you learn which. An open, free-draining mix is needed, so plenty of "sharp" sand (such as crushed quartz sandstone or course river sand), a binding material, such as washed bark fines, coco-peat or peat moss, and a "filler" such as Perlite (I use plastic foam scraped into the mix with a wire brush). Soil is not suitable; it introduces pathogens, and clumps into an impervious 'glug' in the pot. Sawdust does the same. Commercial mixes are required to be made to an Australian standard; but you may need to add ingredients to suit a particular plant (more sand, more vegetable matter etc).
It is a waste to add any fertilizer to the mix, since there are no roots to take up the nutrient. A liquid fertilizer spray on the foliage may be useful.
The mix should be damp, and firmed by tapping the bottom of the tube firmly on a flat surface (not pressed). A hole is made with a dibbler stick, and the cutting placed in the hole without scraping off the rooting hormone or honey.
No mix
Lots of soft stemmed plants will form roots easily when the cuttings, taken in the usual way, are suspended in a glass or small jar of water, and placed on a window sill in good light, but not direct sunlight. Scaevola, Brachyscome, Myoporum and Hibbertia all lend themselves to this method.
The environment
Potted cuttings benefit when the tubes are placed off the ground (impedes invasion by earth worms or ants), out of direct sunlight and drafts, with optimum humidity. It is ideal if you can supply gentle bottom heat, controlled atmosphere in an 'igloo' watered by measured mist spray. The professionals do this, so that they can virtually lay down cutting material all year round.
Cheap alternatives for the amateur include placing the tubes in a larger pot filled with damp mulch (to reduce drying out), covering the tube with the top half of a clear plastic soft-drink bottle (to increase humidity and to aid in watering via the neck), or placing lots of tubes close together under glass or a plastic 'tent'.
Potting on
Cuttings should be potted on as soon as viable roots form. The speed of root formation is very variable, from species to species, and dependent on the growing environment - a vigorous plant like Orthosiphon aristatus (cat's whisker) will fill a tube with roots in a fortnight. Check root formation by inverting the tube and tapping the edge so the cutting and mix fall cleanly into your hand, so the root formation can be inspected.
Another APS member, Cath Daley, uses an especially sandy mix, so she prefers to wash the rooted cuttings gently in water, thus dissolving away the sand for later recovery and reuse and leaving the cuttings with their capillary roots undamaged.
If your mix is firmer and not too damp, it is easy to knock apart to separate the cuttings without damage to roots.
| |
| Further information on plant propagation |
The ASGAP web site contains advice on other simple methods of plant propagation that are well within the scope of the average grower.
Check out the tips on propagation from seed, division, grafting (as well as further advice on growing from cuttings) on our Plant Propagation Pages.
|
|
With species whose young roots are easily damaged, like Grevillea, it is better to propagate with only one cutting per tube, rather than multiple cuttings that will have to be separated and perhaps damaged.
At this stage, fertilizer, such as slow release pellets, can be added to a mix. Take up of fertilizer can be aided by the addition of small quantities of Zeolite or 'rock dust' (ALROC is one proprietary brand of such a product - APS member Mark Snodgrass uses ALROC No 3, which is low phosphorus).
To sum up
All propagators have made their own individual choices in these matters, as a result of constant and repeated little experiments. There seems to be no single "best" way, nor any hard and fast rules to be followed. Be guided by all the "experts", as I continue to be constantly, and start your experiments NOW.
From the newsletter of the Central Coast Group of the Australian Plants Society (June 2003)
[Front Page] [Features] [Departments] [Society Home] [Subscribe]
Australian Plants online - March 2004
Association of Societies for Growing Australian Plants
|
