Almost any shrub can be grown as a dwarf. The technique for growing a dwarf shrub is not terribly difficult, although it is a long-term project and can take several years to fully accomplish.
Growing a dwarf shrub is an art as much as it is a science. Just as an sculptor "feels" a subject within a block of granite, the gardener growing a dwarf shrub must "feel" the shape of the dwarf shrub that they are nurturing. Each shrub will be different, and each gardener will have his own special style for shaping and nurturing their plants.
How to Grow Dwarf Shrubs
Purchase a healthy young shrub, with a main stem no more than eight inches tall, from a reputable nursery or transplant a healthy young shrub from your own garden. If possible, obtain a planting soil that is specially formulated for growing Bonsai (dwarf) plants. A small amount of vitamin B12 may be added to your plant's water to stave off root shock following transplant.
Plant your shrub in a small, decorative pot that will not encourage excess root growth.
Trim excess branches using scissors or pruning shears. Cut away branches that cross other branches, branches that are growing from the same bud as another branch and any branches that are growing from the base of your shrub.
Trim branches for length being certain that you leave at least two bud nodes on each branch that is cut for length.
Your artistic vision for your dwarf shrub should just begin to take shape with this step.
Do not cut away more than 30 percent of the foliage of your shrub at any one cutting.
Water and fertilize your shrub. Allow it to grow for at least one month before doing any more pruning.
Shape your shrub slowly over time. Start by cutting branches with large leaves and branches that are growing too quickly. When pruning, try to leave at least two bud nodes on each branch that you cut to encourage further growth. Add fertilizer at proper intervals for your particular shrub and keep soil moist but not wet. Do not trim again for at least two months. Never cut more than 30 percent of the foliage of your shrub.
Remove your shrub from its pot after one year and carefully shake off at least half of the potting soil. Using your shears or a pair of scissors cut approximately one inch off the end of the main tap root of your shrub and then carefully trim up to two inches off the ends of the larger ancillary roots.
Replant your shrub in its decorative pot, adding additional potting soil if necessary. Water and fertilize. Use a small amount of vitamin B12 for root shock.
Continue making small trims as necessary. Trim branches with large leaves and cut any fast-growing branches, always leaving at least two bud nodes when cutting. Trims should take place every two months.