Bulbs can be propagated in a number of ways. Division can be used for bulbs or corms that grow in clumps, and spring-, such as snowdrops, are best divided while still in full growth after flowering. Daffodil bulbs and crocus corms often have small bulblets or cormlets forming around their base. The largest ones are worth detaching and growing on, allowing between one and three years before they reach flowering size.
Bulbils: Someform little bulbs called bulbils on their stems, and these can be removed and sown like seeds. Remove them from the plain about a fortnight after flowering has finished. Plant in a partially shaded spot with the tips just below the . You can expect a flowering plant within two to three years.
Bulb scaling: This is a useful method of multiplying lilies as you can obtain several plants from just one expensive bulb. Carefully pull away up to six of the fleshy outer scales and place them in a plastic bag containing multipurpose compost.
Close the bag and hang it up in a warm place such as an airing cupboard. After three weeks, roots should have formed on the scales. Each rooted scale can be potted up and grown on; such plants should flower within two or three years.
Using ‘ready-made’ plants
Sometimes, the process of obtaining new plants can be speeded up compared with the conventional cutting technique, by making use of the ‘ready-made’ offspring that some plants produce. The most important among these arewhich are especially significant on , but I must emphasise that strawberries are also among the plants that soon accumulate virus contamination and taking runners from existing old stock will be self-defeating. This is an instance where you will do well to buy fresh stock. The second common type of ready-made plant is the offset. These are familiar as miniature plants growing from the base of many species of Agave, Aloe and other succulents. When removing offsets from parent plants, I prefer first to sever the connection between parent and offspring and then allow the young plant some weeks of independent existence to build up its own root system in situ before it is transplanted.
Some shrubs root poorly from cuttings, commonly because evergreen cuttings lose too much water through their leaves before they have had a chance to root. Layering is a successful alternative technique for such plants. Select a low-growing branch and strip off a section of leaves, starting about 20cm (8in) from the tip. Cut a shallow nick on the underside of the stem and pin the branch down into a shallow trench (if your soil is poor, use a hand fork to dig in some soil amendment or fresh top-soil). Cover the branch with soil. Stake the upright portion of the stem and leave the plant for between six months and two years to develop roots.
This is a technique used on large-leaved evergreens that lack low-hanging branches and an area of bare soil in which to peg them down. Air layering is often used to improve the shape of houseplants such as rubber plants, that have lost a number of their lower leaves. A small cut is made on the main stem and wedged open with a match stick. Moist peal or sphagnum moss is packed around the wound and enclosed in black plastic to retain moisture and keep out the light. The plastic is held in place with sticky tape. The layered stem could take between two months and a year to root, when you should remove the moss and plastic, sever the stem just below the layer and pot up the new plant.