Renewal pruning is a method that stimulates new growth while removing unproductive wood or canes.
According to some, renewal pruning refers specifically to plants that produce canes from the root system. I am going to use the broader definition above. The general rule of thumb for renewal pruning is to remove one-third of any older wood each year. These are thinning cuts that take branches back to the main stem or crown, depending on the growth habit. [When making thinning cuts, be sure to avoid damaging the branch collar.] Each species has its own characteristics, which need to be taken into account before you start lopping off branches. Some of the more common approaches to renewal pruning are listed below.
Renewal pruning of currants
Currants produce fruit on spurs that emerge from 2- and 3-year old wood. After that, those limbs are far less productive. Use the following pruning schedule on currants:
Renewal pruning of fruit trees
Fruit and nut trees produce fruit on spurs and on twig tips. Some species only produce fruit on new spurs, while others can use the same spurs for several years. For example, figs, grapes, persimmon, and quince produce fruit on new shoots and one-year old wood. Pears, walnuts, and apples, on the other hand can produce fruit on the same spurs for several years. UC Davis offers a chart of fruiting wood characteristics that can help you decide what to remove and what to leave for another year. Did you know that large, unproductive branches are called bulls? I didn't either.
Renewal pruning of raspberries and blackberries
Some varieties of raspberry and blackberry produce fruit on primocanes. These are fall-bearing varieties that produce the best fruit on first-year canes. While leaving them in place will provide some fruit the following spring, the quality and quantity are usually poor. For these berries, it is better to cut the canes back to ground level in late autumn. This gives the plant time to pull carbohydrates from the leaves down into the crown and root system. These nutrients will be used to grow new canes in spring. Summer-bearing floricanes produce fruit on buds from second-year canes, so removing them at the end of year one would be problematic.
Some trees and shrubs can become so out of control that they risk falling over, severe disease infestation, or they simply look awful. In some (but not all) of these cases, rejuvenation pruning can be used to give them a new start on life. These plants are cut to ground level and allowed to start over from an established root system. Before you try this method, be sure to research the plant to make sure this is an appropriate choice. Cutting back some plants in this way will kill them.
Whole tree pruning
Traditionally, trees that produce fruit in new growth, such as cherries, are pruned by removing selective branches. Another method being studied is whole tree pruning, in which all the major limbs are removed each winter, leaving only 12 to 18 inch nubs. This method is not for the faint of heart, but it is gaining popularity among commercial growers.
Don’t be afraid to prune your trees and shrubs. It is an excellent way to help your plants to stay healthy and productive. As you move around under the canopy or peaking into the center of your shrub, you may even discover a new pest or disease before it gets out of hand!
I hope this information inspires you to grow more of your own food. You can ask your garden questions on my Home page.