Propagating by Division
Division reproduces plants asexually, resulting in genetically identical offspring, with all the original desirable and undesirable attributes. Many plants naturally reproduce by division, some much more readily than by seed. It is also easy, and produces more mature specimens quickly.
Water plants well for the two days prior to dividing. This is best done in cooler weather or later in the day. Divide after the plants have finished flowering, or in spring, for fall-flowering species.
Knock plants from pots, or dig up, and pull the rootball into sections, each containing part of the crown and a few good roots to support it. The root-ball often falls easily into a few discrete clumps: use nature to guide you. A knife or pair of pitchforks may be needed to separate tougher root systems, and with some plants, such as Astilbe, an old saw may be needed to cut them apart.
Both long leaves and long roots should be trimmed back, and dead or diseased parts of the clump discarded. Each new section needs both healthy roots and shoots. Replant immediately and water well, and protect from strong light and cold for several weeks.
Rhizomes or tubers can often be cut into pieces, each with one or more shoots, buds, or bud eyes. Replant, and protect several days. Suckers may also be cut or pulled off, each with a good root network, and should similarly be protected.
Plantlets produced on runners may be rooted while attached to parent plant, or be freed then planted into warm moist soil. Protect from sun for a week or two.
Some of the cylindrical cacti produce smaller plants at their bases: pull them off, leave to form a callus over a week or two, then pot.
Orchids from Pseudobulbs
Plants with a liberal number of mature pseudobulbs may be divided into smaller sections each with 3 to 5 pseudobulbs. Select pots that will allow 2 to 3 years of growth before crowding. Fill the new pot with a small heap of fir bark, cut off rotten roots from the specimen, then spread roots over this heap. Pack moist medium firmly around roots, and stake if necessary. Keep the plant humid, shaded and dry at the roots, but well misted, for a few weeks to promote new root growth. A vitamin B1 solution may help.
If, at the time of division, few healthy roots are present on a set of pseudo-bulbs, keep in damp sphagnum moss, out of direct sunlight, mist regular-ly and keep humid until root formation is well underway. Pot up into pre-soaked mix, water again, and keep lightly shaded for a few more weeks. Mist regularly but water sparingly until ready to move into normal growing environment.
Bulbs without leaves are considered backbulbs; while these may also be divided off, they need special care to grow. Either leave backbulbs on a division to add strength, or take single backbulbs, and grow them on in a well-drained bark or peat/sand mix. Bury them halfway, and keep shaded and warm until new growth appears, then pot on as above. It may take up to three years to produce a good-sized plant by this method.
