Lots of gardeners are intimidated by the very thought of pruning. It can be scary.

For trees and shrubs that are grown for their flowers, consider when they bloom before deciding when to prune. Snip at the wrong time and shrubs and trees will not put on their much-anticipated spring flower show. However, many plants can be pruned during the winter and early spring.

Pruning at any time of year — whether it is the “best” time or not — likely will not kill or permanently damage your plants, even if you do something wrong when you prune.

So, what should you prune at this time of year? 

You can take your pruning shears from now through early spring to non-flowering evergreen and deciduous trees and shrubs. These can include foundation plantings as well as screens and hedges such as boxwoods, yaupons, yews, distylium, euonymus, junipers, hollies, cleyera, photinia and wax myrtle.

You can also prune ornamental grasses and tropical plants, but be cautious when pruning "dead" things.

Tropical plants will undoubtedly be fooled by our weather. One week, we are in the 40s; the next, we are in the 80s. You can trim now, but be aware that the next cold snap will zap the new tender growth encouraged by a brief warm spell. This can stress the plants, but they will survive. Also, birds and animals love dormant clumps of grass for eating, nesting and hiding. 

You also can prune summer-flowering shrubs and trees that set their flower buds on new growth that resumes in the spring and early summer. Some summer-blooming plants are abelia, althea, cassia, crape myrtle, oleander and vitex. Now is a good time to trim them up because it's easier to see the tree form without leaves.

Now that you know what you can prune, you need to consider the best way to prune. Pruning can simply be removing crossing branches. Some folks use the “heading back” technique — shortening shoots or branches to stimulate growth, control size, encourage fullness and maintain specific shapes. You also can thin out select branches at their point of origin.

What not to prune?

Do not take shears to spring-flowering trees and shrubs that bloom from January through April. Buds are set on last year's growth, and removing branches would remove those soon-to-be flower buds.

So, don't touch some of these most common spring-flowering trees and shrubs: azalea, banana shrub, camellia, deutzia, Indian hawthorn, Japanese magnolia, star magnolia, Taiwan flowering cherry tree, spirea, quince and wisteria.

But what about flowering shrubs that bloom on old wood? These are much like our spring bloomers, but are late bloomers, meaning they don't flower until early summer. These late bloomers form next year’s flower buds in late summer or early fall when the days become shorter and the weather cools. These shrubs should be pruned shortly after they have stopped blooming in the summer.

Some examples of late bloomers are climbing roses, gardenias, hydrangeas (bigleaf and oakleaf) and garden roses (not the ever-blooming types). 

There are also repeat bloomers, such as Encore azaleas and Knock Out roses, which bloom in the spring and again in the fall and sometimes in between. What do we do with them?

A good rule of thumb for all flowering plants is: Prune shortly after they have completed their bloom. Whether the buds are set on new growth or old growth, if you prune right after the bloom and before new blooms set, you will be just fine.


Email questions to gardennews@agcenter.lsu.edu.