Most indoor plants can be increased fairly readily fromor offsets, often by division, and sometimes by . Raising from is normally too lengthy. Cuttings and offsets Cuttings are pieces of , occasionally separate , or sometimes a with a piece of attached. A few will in the open, or in water, but it is better to use a closed propa-gating case – a seed box supplied with glass sides bound with sticky tape and with a glass lid is quite suitable, or a more elaborate case may be made or bought. This must be kept out of direct sunlight.
The best time for rooting cuttings is in summer, unless bottom heat is available when rooting can start in spring. Sharp sand or vermiculite, or a mixture of these with peat, is used as a rooting medium. It should be kept fairly damp. If only one or two cuttings are wanted, a jam-jar or polythene bag over a pot can replace the case. Cuttings of woody plants will root quicker ifrooting powders are used.
As soon as thehas rooted, pot it up in an individual pot of light, sandy soil, and acclimatise it carefully to the room conditions.
Offsets are small growths produced round certain plants (i.e., clivias), and they can be grown on like cuttings. They can often be taken with some , when they should be treated like newly rooted cuttings, and potted into small . Division Many plants can be increased by division of clumps; this should be done with care so as not to damage too many roots. Water carefully for a time after dividing, which is best done in late spring. This consists of bending a branch into a pot of soil, where it is firmly pegged, preferably into the lower surface of the piece underground to provide a ‘tongue’, as with carnations. Hormone rooting powders can be dusted into the cut with advantage. When roots have been formed, the layer can be cut off from the parent. Also known as Chinese layering, this is ideal for plants such as Ficus, and which become leggy due to the lower leaves falling. Though the tops of these can be used as cuttings, a good deal of heat is needed for success. To make an air layer, either make a slit about I in. long into the stem, from below upwards, and push a sliver of wood into it to hold it open, or cut out a ring of bark about \ in. wide, in each case at the point where roots are wanted. Dust the cut with a if available. Next, bind a handful of moist sphagnum moss or peat around the cut with a few turns of thread, and then surround this with polythene sheet (or a polythene bag cut open), overlapping it well and tying firmly top and bottom. A few weeks after roots show through the moss the stem may be cut below the moss ball and the new plant can be carefully potted up. Make sure plenty of roots have formed before cutting the stem: usually at least eight weeks is necessary for this. The old stem will sprout again, usually near the point of cut, or it may be reduced further to ensure more attractive new growth nearer the base of the old plant. For it is best to use only the top of the plant, say the upper 12-24 in., where the stem is the least woody.