Fall Tree and Shrub Care: Is It Time to Prune or Fertilize?
Fall is a great season to accomplish garden jobs like planting. But you may wonder if this is the time to prune trees and shrubs, or if woody plants can be fertilized in autumn. Here’s what you need to know:
Can I prune trees and shrubs in the fall?
It's usually not a good idea to prune trees or shrubs in the fall, for a couple of reasons.
First, pruning can trigger a flush of new growth. If this occurs in the fall, the new growth may not have time to harden before freezing weather sets in, leading to damage.
Secondly, if the tree or shrub in question flowers on "old wood" (in other words, it has already set its flower buds that will open next spring or summer), then pruning in the fall would remove them and diminish next year's flower display.
So wait until midwinter to prune trees and shrubs that will form flower buds on new wood in the spring. For trees and shrubs that set buds on old wood, like bigleaf hydrangea (Hydrangea macrophylla), forsythia and ninebark (Physocarpus opulifolius), wait until right after the plant blooms next year to prune.
Related: How to plant a shrub in the fall.
Can I feed trees and shrubs in the fall?
As for fertilizing, don’t do it in early fall. Doing so could stimulate new growth that will be susceptible to winter injury. And don’t feed newly planted trees and shrubs; their roots need time to heal and establish in the soil.
That said, late fall is actually a great time to fertilize established trees and shrubs if they seem to need a boost. Fall is the prime time for trees and shrubs to put out new roots, and plants are storing energy reserves now, so any fertilizer applied in late fall will support next year’s growth.
However, if trees and shrubs are healthy and growing well, feeding is not necessary! Your time may be better spent attending to soil health in the fall, which ultimately supports your plants, too.
Related: 5 ways to improve your soil in the fall.
Should your trees and shrubs exhibit signs of poor health, such as little growth, reduced leaf size, pale leaf color and branch die back, you may want to feed them. (Related: More reasons a tree or shrub may need fertilizer.) In the fall, fertilizer can be applied when new growth has ceased and the leaves have dropped (if deciduous), the air temperatures have begun to moderate (no warm spells expected) and the soil is holding moisture. In general, wait several weeks after the first frost to apply fertilizer. Follow the package instructions for how much to apply.
