Some bulbs produce offsets that can be detached and grown on to flowering size, or they can be cut into sections and persuaded to produce several new plants. Most bulb propagation is best done when the bulbs are dormant.
What methods can I use to propagate bulbs?
You can increase your stocks of
bulbs using a variety of methods. Many species are easily raised from seed. Depending on how the bulbs grow, you can either detach small bulblets or cut up a dormant bulb
into sections or ‘chips’.
What equipment do I need to propagate bulbs?
You need no special equipment for cutting up bulbs, but good hygiene is of paramount importance. All cut surfaces should be treated with a fungicide to prevent rotting. You can use either a fungicidal powder or a liquid. Wear rubber surgical gloves when handling the bulbs – this protects your hands (some people experience an allergic reaction) and also protects the bulbs from bacteria, which can cause rots.
What are offsets?
If you look at the base of a dormant bulb such as a daffodil, you will
see that the roots emerge from a toughened disc – the basal plate.
As part of its growth cycle, new bulbs emerge from around the basal plate annually, and in time the central bulb withers and dies back. If you dig up clumps of bulbs after flowering – but while they are still in full leaf – you should be able to tease them apart and separate the smaller bulbs. You can either pot these up for growing on or return them to the garden. Discard any old, withered bulbs.
Which bulbs produce offsets?
How do I propagate bulbs
Chipping is a good method for increasing stocks of bulbs that do
not readily produce offsets, although you can also use this technique on these as well. Take a dormant bulb and trim back the growing tip.
Also trim back the roots, but take
care not to damage the basal plate. Holding the bulb upright, cut it
in half with a sharp knife. Cut each
half in half again. You can carry on dividing each section as far as is practical – you should get up to
16 chips, but it is important that each one has a scrap of basal plate at the bottom, as it is from this that the new bulblet will form.
Half-fill clear plastic bags with perlite or vermiculite, dampened with a little liquid fungicide. Dip each
chip into a liquid fungicide, then
put a few chips in each bag. Blow up the bags and seal them with rubber bands or wire ties. Shake them to distribute the chips. Keep the bags in a warm, dark place, such as an airing cupboard. Check them after about six weeks. Within 12 weeks, new bulblets
should have formed on the basal plate and the chips themselves should be blackening. Remove the chips and snap off the bulblets. Pot them up
and grow them on – they should reach flowering size within two to three years.
Which bulbs can I propagate
What are cormels?
Technically, gladioli grow not from bulbs but from corms – a flattened disc of tough stem tissue that stays underground. Each corm produces little corms – or cormels – around
the basal plate. To propagate using these, dig up the plants after
flowering and as the foliage is dying back. Allow them to dry out in the sun, then store the corms in a cool, dry place over winter. In late winter
to early spring, snap off the cormels from the base of the corm and pot them up. Grow them on in containers, protecting them from frost over winter. Two to three years later,
they should have reached flowering size and can be planted out in
How can I propagate dahlias?
Dahlias grow from underground tubers – swollen roots like a
potato. To increase your stocks, in spring, arrange the tubers on trays of potting mix, pressing them into it without burying them. When a tuber starts to shoot, lift it from the potting mix and cut it into sections with a sharp knife. Each section should have at least one shoot. Dust the cut surfaces with a fungicide, then pot up the sections and grow them on. Water and feed them well. They should be well enough established to plant out in late spring and should flower the same year.
How do I take basal cuttings
You can also propagate dahlias by cuttings. If they are to flower the
same year, take them as early as possible. Coax the dormant tubers into life in late winter by arranging them on trays of potting mix, then keeping them warm at 15–18°C (60–65°F). When the shoots have
two or three pairs of leaves, cut
them from the tuber, with a small piece of tuber tissue at the base. Trim off the lower leaves. Pot up the cuttings, then place them in a
heated propagator. Once rooted, pot them on and gradually harden them off. Protect the cuttings from frost. They should be ready for planting
out in late spring.
Propagating dahlias 1: In late winter, place dahlia tubers on trays filled with moist potting mix.
Propagating dahlias 2: Use the new shoots as cuttings. Each should have a tiny section of the tuber at its base.
Propagating dahlias 3: Treat the base of each
cutting with a hormone rooting compound, then plant them up
in plastic pots.
Propagating tuberous begonias 1: In late winter, cut the tuber into sections, each with at least one bud.
Propagating tuberous begonias 2: Dust the cut surfaces with a fungicidal powder to prevent rotting.
Propagating tuberous begonias 3: Half bury each cut section in damp potting mix, in pots or trays.