Generally speaking, the best time to trim trees is in early spring before they start their new growth for the year. This allows them to heal during a time of heavy growth. Pruning and trimming after this growth takes place means that the energy expended on the trimmed areas was wasted. However, it's possible to trim most trees at any time of year if necessary for health or safety. It may take a tree longer to heal if it is trimmed in late spring or summer, but unless the tree is already weak and unhealthy, it will recover in time.
Certain types of trees, however, have some special considerations when planning a trimming. Some of them are simply aesthetic, but others can have a big impact on the health of your tree.
Trimming a flowering tree in early spring is a job best left to professionals, and even they may recommend that you wait to trim if possible. This is because, for almost all flowering trees, the areas on the tree that will bud and flower have already been determined before the tree goes dormant in the winter.
That means that spring pruning can easily remove areas that would have flowered, and the tree has no way to make up for this. You may end up with patchy blossoming or even, in extreme cases, no flowers at all. Instead, trim flowering trees a few weeks after their blossoms have dropped.
Maple and Birch
Maple and birch are the most common "bleeding" trees. If they are trimmed in late fall or early spring, they often bleed sap from any pruned spots. This isn't really a problem for the tree; the sap will eventually slow and stop. However, it can be very unsightly, so many people avoid trimming maples and birches during these seasons.
To avoid bleeding, trim these trees when they are fully dormant in winter or when they are fully leafed out in the summer.
The timing of trimming oak trees is crucial to their health. Oak wilt is a disease caused by fungal infection of both red and white oaks, and once a tree is infected, oak wilt is fatal. One way that the disease is spread is by beetles that are attracted to the sap of oak trees. When these beetles land on the tree and feed on the sap, the fungus enters the tree.
Since they are attracted to sap and an oak tree that is trimmed will have exposed sap, it's important to trim oak trees only during cold weather. The beetles go dormant in cold temperatures, so wait for the daytime high to drop below 50 degrees before trimming an oak tree. For more tree trimming help, contact a local tree service, like Destiny's Tree Service LLC.