Semi hardwood cuttings are taken when a plant has finished its growth rush for the year. The wood is firm, but not really hard. These are sometimes called half-ripe cuttings, semi-ripe or green wood cuttings. In contrast, softwood cuttings come from tissue that is soft (usually spring growth), and hardwood cuttings come from older, harder wood (usually taken in winter).
HOW TO MAKE A CUTTING
Cut off a piece of stem containing leaves
Remove 60-75% of the leaves (It’s OK to cut a big leaf in half)
Fill a pot with a loose, clean propagating mix (eg. Perlite or a sand/peat mix)
Dip cuttings into a hormone (to stimulate root growth) –obtained from nurseries
Push a hole in the mix with a pencil size stick
Plant the cutting 50-60% into the mix & push the mix around it with the stick
Water well and put in a warm place
LOOKING AFTER CUTTINGS
Keep the cuttings moist, but not wet. You need to protect the cuttings from extremes of temperature and moisture. Ways to do this include:
putting the pots on a warm window sill or enclosed verandah
using a cloche, which is a small plastic or glass cover placed over plants
using a cold frame, which is a fixed rectangular frame of brick, timber etc with a sloping glass lid. The sloping glass lid allows condensation to build up and run off back into the growth media.
Putting the cuttings in a greenhouse. In a greenhouse, temperature, humidity and hygiene are strictly controlled – perfect for cuttings. Heated benches also increase the amount and speed of root formation.
A plastic soft drink bottle with the “funnel top” removed can be turned upside down over a cutting to protect the cutting from heat and cold, and to keep it moist.
PLANTS TO PROPAGATE FROM SEMI HARDWOOD CUTTINGS NOW
It’s a great time of year to take semi hardwood cuttings from
Many Australian native shrubs and woody herbs
Evergreen Azaleas are relatively easy to propagate in late summer or autumn, after the summer heat and before the winter cold.
Take a cutting from a tip of a shoot, perhaps 4-7cm long. Carefully remove all but the top two leaves and bud.
Treat with a root hormone (eg. IBA powder or liquid)
Plant the cuttings into trays or pots of a standard propagating mix, then place the containers in a hotbed and/or greenhouse until the cuttings have rooted.
You can treat Azalea cuttings with an alkaline solution before putting on the hormone. Stand the prepared cuttings for 10 minutes in a diluted solution of Sodium Hydroxide. This reduces water loss from the cutting, hence reducing stress as it forms roots.
If you have a propagating bed, they do very well under misting if in a very well drained medium.
Otherwise, put your pot of cuttings in a sunny spot inside the house (Not too hot or cold); and water whenever it needs it (don’t allow the pot to dry out, but don’t saturate it when it is already wet.
Use only sharp, clean secateurs to collect cuttings.
Disinfect your tools (eg with methylated spirits) before use, to reduce disease outbreaks
Most shrubby Grevilleas form roots easily. Trees such as G. robusta are often difficult from cuttings, and are propagated by seed. Whilst some hybrids can be tricky to propagate, but they are usually done by cuttings.
Cut off a piece of stem that has leaves and green wood.
Dip the cutting in a rooting hormone treatment (ask your nurseryman for this)
Plant the cuttings in trays, and if you have access to it, use a heated bench and misting. Otherwise, place the cuttings in a warm spot where they won’t dry out.