For most gardeners, there’s always room in the garden for more plants. Propagation (a way of creating plants from existing ones) can boost your collection utilising what you already have.
D.I.Y. plant propagation is cost-effective and it’s also a lovely way to share your plants with friends and family. “It’s fun, feel-good and fills you with joy,” says Gopika Sambantham, founder of SFA Landscape Design (@design.sfalandscape).
There are several plant propagation techniques you can add to your gardening skills – read on to find out how to start your own little plant factory!
Safety tip: Always wear the appropriate safety equipment (gloves and a mask, for example) when handling potting mix and always follow the instructions for the product or equipment. Always store products out of the reach of children and pets.
Seeds are one of nature’s wonderful gifts. They contain everything needed to grow a plant from scratch, neatly bundled in a tiny package. Most plants can be grown from seed, although some are trickier than others and may require extra measures, such as soaking or scarification (weakening the seed coating) to encourage germination.
Seed sowing requirements vary according to plant type, so Bianca Boman of Mr Fothergill’s recommends following the instructions on each seed pack to get the best results.
You can collect and use your own seed from most plants. Seed heads are produced once flowers are finished, so don’t deadhead blooms if you want to collect seed. The process varies between plants, so it’s best to do a little research first. For example, you can harvest seed from ripe tomatoes, but for coriander, you need to wait for the seedpods to dry before collecting them.
Ideally, seed should be collected from open-pollinated varieties – that is, plants pollinated by natural means, as opposed to hybrid plants. Hybrids have been artificially crossed to produce plants with desirable traits, but the seeds from these are not likely to grow ‘true to type’ and resulting plants will be different from the hybrid.
Top picks: sunflower, cosmos, heirloom vegies, sweet pea, and billy buttons.
Dividing plants involves removing and replanting a section of the parent plant that has its own roots. This plant propagation technique works best with evergreen and herbaceous perennials that have a clumping habit, such as hostas, clivias, salvias, kangaroo paws and some ornamental grasses.
Over time, as these plants spread, they can become crowded and won’t perform or flower as well as they used to. Splitting plants like these gives you more stock to fill gaps and keeps the parent plants looking their best.
To divide a clump, dig around the edge of the plant and use a garden fork to lift it carefully from the ground or pot. Gently tease the root ball apart. If it’s difficult to work with, use a sharp knife or spade to divide it, ensuring each section has viable roots and shoots.
“Replant or repot each plant in a good-quality potting mix and water regularly to keep the mix moist,” advises Bianca.
Tip: Most perennials and some ornamental grasses should be divided in winter or early spring, before new growth has started.
Top picks: lamb’s ear, mondo grass, dianthus, dahlia, and iris.
For many indoor and perennial plants, the easiest propagation method involves taking stem cuttings. Choose a firm, healthy stem and take a cutting at least 15cm long with a couple of nodes. Trim the base just below a leaf node and remove lower foliage, leaving a pair of leaves at the top.
To achieve the best propagation results and promote root development, Gopika suggests dipping the base of the cutting into rooting hormone before inserting it into a pot filled with moistened propagating mix. Position in a brightly lit spot out of direct sunlight, and water regularly to keep the soil moist. You can also use a mini greenhouse or plastic cloche to maintain warmth and humidity.
If propagating indoors or during cooler months, Bianca recommends a heat pad. “An electric heat pad helps mimic spring soil temperatures, encouraging the cuttings to put energy into developing roots and shoots faster,” she says.
Stem cuttings can also be propagated in water. Instead of inserting cuttings into a propagating mix, place them in a glass of water. “Change the water weekly and, when enough roots form, transplant into individual pots,” says Bianca.
Top picks: rosemary, hydrangea, coleus, buxus, camellia, geranium and most indoor plants, including devil’s ivy, philodendron and monstera.
Layering is a plant propagation technique that encourages the parent plant to produce new plants, which remain attached while they grow roots. Once healthy roots have formed, the new plants can be severed and transplanted.
“Layering works best with plants like monstera and devil’s ivy that develop aerial roots,” says Bianca. “It also works well for plants like strawberries that root easily when nodes touch the ground.”
Layering is best done in spring and summer when plants are actively growing. “Bend stems downwards, pin the nodes to the ground and lightly cover with soil,” says Bianca.
For indoor plants, especially those with thicker stems like philodendrons and monstera, try air layering. Cover a node with moistened sphagnum moss and wrap with plastic to keep it moist. When roots form, the new plant is ready to be detached and transplanted.
Top picks: blackberries, strawberries, English ivy, and rhododendron.
Check out our five easy steps for propagating in a greenhouse.
Some products are not available at all Bunnings stores, but may be ordered.
Photo Credit: Gap Photos, Lynn Keddie, Anna Robinson, Wild Violet Flower Farm, Janet Johnson, Cath Muscat.