Most plants reproduce by seed, but this can be hampered by several factors. For example, adverse weather conditions can reduce insect populations and pollination. To counter such problems, plants have evolved backup methods. Perennials often form large clumps made up of many small plantlets that can survive on their own. Other plants can regenerate from a section of root or stem separated from the main plant, and the flexible stems of climbers and some shrubs take root if they rest on the soil. These traits are exploited by gardeners to make new plants.
A few basic items are essential for successful propagation. You will
need a pencil or waterproof pen and labels for identifying plants;
pruners and a sharp knife for taking cuttings; plastic bags, and elastic
bands to secure the bags over pots; a small sieve for dusting soil over
seeds; a block or piece of board for firming soil before sowing; and a
dibber or pencil to make planting holes and lift seedlings.
Trays, Modules, and Pots
Seed trays are useful for raising large quantities of seeds. The usual
size is about 14 x 9 in (35 x 23 cm); half-size trays are also
available. Module or multicelled trays have a number of internal
divisions, each treated as a separate small pot. These eliminate the
need to prick out young seedlings and are useful for minimizing root
disturbance or growing several different plant varieties together.
Root-trainers are deep modules with ridged sides to help long roots grow
For single or small numbers of seeds or cuttings, 3–31⁄2-in (8–9 cm)
pots are the most suitable size; for larger quantities, 5–6-in
(13–15-cm) pots are more economical. Plastic pots are easier to use than
clay ones, and retain moisture for longer; either type must have
drainage holes at the bottom. Biodegradable pots eliminate root
disturbance when seedlings are transplanted to larger pots or outside
into the ground. As your seedlings grow, they will have to be moved
outside to harden off.