Trees and shrubs are increased by: 1. Seed; 2. Division, layers or cuttings; 3. Budding and grafting.

Seed
This method is slow and in some cases impossible for trees because many foreign species fail to produce seed until they are quite old. A number will not fruit at all in this country.

Shrubs are often more rapid and the method is extensively used for species of Cotoneasters, Roses, Berberis and other berried plants. Many trees and shrubs, however, have certain characteristics which are different from the type, such as doubling in the flowers, colour changes or foliage variegations. These cannot be reproduced from seed.

Tree and shrub seed varies considerably, some being very small, others large and tough coated. They may take years to germinate or may come up almost immediately.

Vegetative Reproduction
Practically the whole gamut of plant propagation is practised in one form or another on trees and shrubs. Cuttings, layers, grafting, budding, division, root-cuttings, air layering and tip layering are all used.