The short answer is NO. Many people have seen or heard of wound sealants and wonder if they should be using them for the tree’s health. The tree care industry has done a 180 on this topic, from advocating to discouraging their use, which has confused many. This was a common practice decades ago; old tree care texts recommended it and sealant products are still sold at many garden centers. Many substances had been used from roofing tar to latex house paints. It was believed that using these on trees kept out fungi after a cut exposed its vascular tissues.
Research has since shown that tree cuts need open air to trigger natural wound sealing properties. Trees contain chemicals that inhibit fungi and resist decay in the area where a branch meets the main trunk. This area, called the branch collar, is where we are supposed to make our final pruning cut when removing a branch for this very reason. Therefore, the best way to guard against fungi and decay development is to make accurate and judicious cuts and let them breathe.
Are you wondering why your shrubs didn’t have many flowers or any at all? Here are a handful of reasons why this can happen and some solutions to consider.
- Flower buds were pruned/sheared off last season. Many shrubs such as Lilac, Rhododendron and Azalea flower on previous season’s wood so if they are pruned in the months after their flower buds have set, there will be no/fewer flowers the following season. Prune immediately after flowers pass.
- Not enough sun. Even plants that survive in the shade may not flower as well as the same plant in a sunny spot. Prune or thin over hanging trees or transplant to a better spot.
- Buds have been frozen by a late freeze. which is often the case with Hydrangea. There are hardier Hydrangea species to choose from and some cultivars will even repeat bloom.
- Not adequate soil nutrition. Fertilize and add compost to improve soil conditions.
- Lack of vigor/energy. Usually this happens in shrubs that are very old and overgrown. A hard rejuvenation prune in spring can stimulate new growth and fresh start. Keep in mind that it most likely won’t flower during the first year of this new growth.
- Species has less showy or noticeable flowers than you would have thought. Remember some trees and shrubs have separate male and female flowers. Look closely.
- Has pests attacking it. Your shrub may be prioritizing its energy reserves to staying alive, thus sacrificing flower development.
- It can depend on the weather. The duration and harshness of each season will yield brighter or duller, numerous or fewer blooms.
Deciding when to prune/trim is confusing to many people because there is no one-size-fits-all answer and even the experts can’t always agree. Yet, it is the most commonly asked question of gardeners, landscapers and arborists! Pruning of live branches is not as critical as many people think, but it is worthy of discussion.
The Best Times for Pruning: (the opposite of Part 1; Worst Times)
- A mild, dry and seasonal day
- When the plant is healthy and hasn’t recently been disturbed by construction, storms and/or heavy pruning
- It depends on how much you plan to cut off;
A Heavy Trim >50% cutbacks of shrubs, the best time is late winter, early spring
A Medium Trim ~25% maximum amount to remove annually, early spring and summer
A Light Trim <15% anytime of season
- It also depends on whether or not you will miss the full flower effect;
If you won’t miss some of the blooms, prune anytime of season
For plants that bloom on current season growth, in late winter, early spring
For plants that bloom on previous season growth, right after bloom
- Lastly, Dead branches can be pruned anytime!
In general, the optimal times for ornamental tree and shrub trimming is early spring and summer and those should be the go-to times if you are unsure. Don’t let timing keep you from grabbing your pruners if a haircut is truly needed and you just can’t wait!
If you are trying to figure to out the best time to prune/trim, start first with the worst times to prune (because more experts agree on these) and work backwards from there.
So, what are the worst case scenarios in pruning at the ‘wrong time’?
- loss of flowers/fruit
- health decline/injury
- and/or death
One important point is that pruning at the ‘wrong’ time of year probably won’t kill your tree or shrub, but it may weaken it in the long run. Indeed many plants are trimmed at less than ideal times and yet they survive.
The Worst Times for Pruning:
- In the rain. Many bacterial and fungal diseases are spread during cold or hot wet weather and fresh cuts make easy access.
- During a severe drought, or flood like conditions. Energy is precious at these times and taking off branches is adding additional stress.
- When current or upcoming temperatures are extreme. Fresh cuts are open, exposed living cell tissue that can dry out or freeze and the wood surrounding the cut can dieback.
- When your tree or shrub is unhealthy. Wait for it to recover by giving it time and treatment (if necessary) before pruning.
- After storm damage, root injury (like construction) or heavy pruning. Plants need time to recover from loss of branches and roots before any trimming is done.
- Right before bloom. Does this really need explaining? Well, OK, maybe flowers and fruit aren’t your first priority.
Stay tuned for the When To Trim, Part 2 next month.