Pruning plants is for many people so intimidating that they never do it. While this rarely causes a plant to fail, it means that for some plants their full beauty is not revealed. You have the power to direct the growth pattern of trees, flowers, and shrubs.
The energy in a plant constantly flows to the terminal buds throughout the plant. By pinching out terminal buds you can direct the growth of the plant. Pinch out buds on the right side of the plant and, until new terminal buds are formed, energy flows to the left side and to the top. To be successful at pruning requires some study of the growth of plants, and some experimental pruning. The reaction to pruning differs between different kinds of plants. With some plants pinching out a tip is followed by a quick growth of buds just below the cut; in other plants tip pinching is followed by growth of many lateral twigs all along the tipped branch. It’s a good idea to test the reaction to pruning by making a minor cut or two before you attempt to change the structure of the plant.
You can also direct growth when you cut back a stem to a bud; the position of the bud determines the direction of new growth. If the bud is on the right side the new branch will grow to the right. You can make a shrub more open or denser by selecting the position of the buds below the cut.
Directing the growth of annuals and perennials is a common practice. When planting annuals and perennials such as zinnias, petunias, marigolds, geraniums, etc. pinch out the tips, or terminal buds, for full, many branched plants. Snapdragons should be pinched when they have only 4 or 5 sets of leaves, marigolds and zinnias when the first flower bud is formed. You direct the growth again when you remove faded flowers. Annuals direct their energy to seed production. To stop seed production and increase the flowering, remove the faded flowers. When pinching out faded flowers be sure to pinch below the seed case and not just pulling out the blossom.
When pruning deciduous shrubs and trees you are pruning for renewal. When a portion of a dormant plant is removed, the remaining parts of the plant will receive a larger share of the food stored in the roots, trunk, and limbs. You don’t stimulate root growth by pruning out top growth. The new growth in spring is supported by food manufactured in the previous summer. In late summer and fall, large amounts of the food manufactured by the leaves are stored in the roots, trunk, and limbs. Many deciduous shrubs are pruned for gradual renewal by thinning out old wood. Every year or two you take out a few of the oldest canes at ground level. Removing old wood opens the top to let light and air into the center of the plant encouraging growth from the base that will eventually renew the top.
Summer flowering shrubs are pruned in the dormant season. The flowers are formed on new wood developed in the spring. Spring flowering shrubs are pruned right after flowering as their flowers are formed on last year’s wood. If pruning is needed to keep plants in scale for landscaping effects, do it in spring just before the new growth starts. Prune to retain the natural form of the plants. Selective thinning and heading back will do it.
These are some of the basics of pruning. When you are unsure of the right way to prune talk to your favorite landscape professional for advice. Remember it is better to prune a little less than needed than to prune more than needed. Keep a light hand with pruning until you become more confident.