Here's When Pruning Trees in Summer Is OK—and When It's Not, According to an Arborist

Proper tree care often involves pruning. While the technique is important, timing also plays a role in the tree's well-being. We asked expert Ben Vaughan, a certified arborist who serves as urban forestry manager for the non-profit Trees Forever, whether it's okay to prune trees in the summer. Here's what you should consider before getting out the pruning saw during the warmer months.

Best Time to Prune Trees

Sometimes trees need to be pruned immediately, regardless of the season. Broken, diseased, and dead branches should be removed as soon as possible, especially if they pose a safety hazard. Other pruning is best done at certain times of the year.

"The best time to prune for the majority of woody deciduous plants is February and March,” Vaughan says. “During this period, trees, as well as pests, are dormant, which limits the risk of infection. Additionally, pruning later in winter means that the tree can begin its compartmentalization process immediately in April, rather than having the wound exposed throughout the coldest months of the season."

Case-by-Case Basis

While spring pruning is recommended, Vaughan says there are certain instances where summer pruning is called for. “While some species may face increased odds of infection, minor pruning in early to mid-summer can also invigorate summer growth," he says. "For instance, removing low lateral branches can encourage growth of the tree’s main leader.”

Waiting too long, however, can lead to problems. “The timing of summer pruning can make a big difference in terms of risk and future tree growth,” Vaughan says. “Pruning in the late summer is not recommended for woody deciduous plants in general because the new growth encouraged by pruning does not have time to harden before freezing temperatures, causing the tree to experience winter dieback.”

Risks of Pruning in the Summer

Summer pruning can pose more risks to certain trees species than others. “Identifying the tree in question can be helpful in determining the risk level of pruning, as vulnerability to pests and disease vary greatly between different tree species,” Vaughan says. 

Pests and Diseases

Any time a tree’s live tissue is cut, a wound is created. This wound is an access point for pests and diseases. “Because pests and pathogens are active during the warm months between frosts, summer pruning of live branches is not recommended for vulnerable species,” Vaughan says. 

Two prime examples are oaks and elms because beetles are most active in the summer and are more likely to transmit oak wilt or Dutch elm disease. “Pruning while these pathogens are active increases the odds of fungal infection through stress, which can weaken a tree’s defenses, and from the wound itself," Vaughan says.

Stress to the Tree

Vaughan also cautions against pruning spring- and summer-flowering trees while they are still in bloom. “Pruning while in bloom causes more energy to be put into short-term flower production and can cause stress to the tree.” He says pruning after flowers have dropped allows the tree to focus on creating new growth and buds for the following year.

“Stress from summer over-pruning can result in waterspouts,” Vaughan says, referring to the shoots that arise from the base of a tree. "Overall, summer pruning should be limited to minor branch reductions and removals and removal of dead or injured branches.”

The Bottom Line

Ultimately, summer weather is not conducive to tree pruning. Vaughan says overly wet or dry conditions cause stress to trees, making summer less ideal for pruning. Warm and wet conditions lead to increased risk of damage from insects and fungi, and extremely dry conditions increase the chance of negative stress response, such as weak growth and waterspouts.