Consider the safest timing when pruning spruce trees. Spruce trees are more winter hardy than other evergreen trees, giving gardeners a wide window of time to prune. Sometimes a carefully timed trim is exactly what spruce trees need.
Reasons to Prune
Young spruce trees need training when establishing themselves, but mature spruce trees rarely require pruning. The main reason for pruning an established spruce is removing branches suffering from insect infestations or diseases. Remove broken branches and prune back a spruce tree that's hanging over a neighbour's fence or threatening power lines.
Seasonal timing is not critical for light trims. Colorado State University Extension horticulturalists characterise a major trim as one removing more than 10 per cent of a tree's foliage. For these jobs, waiting until the dormant period in late winter is safest. Because they love the cold, spruce trees differ from other evergreens and endure pruning at any time in the autumn or winter without a great risk of winter injury. Christmas tree farmers prune spruce trees from August through mid-April, according to horticulturalist Fred K. Buscher on Cornell University Cooperative Extension website.
Spruce trees handle cold weather, but when pruning diseased branches, dry weather is safest for their health. In wet weather, tools are more easily contaminated, increasing the risk of spreading one branch's disease to another. Wait for several dry weather days, as the University of Idaho bulletin "How to Prune Coniferous Evergreen Trees" recommends, and disinfect your tools between branches.
An annual, extensive pruning job is more stressful on a spruce tree's health than several light trims spread out through the year. However, constant pruning causes needles to turn brown or die. If this is a problem, remove the branch and refrain from pruning so frequently. As with other evergreens, spruce trees are healthiest when allowed to grow naturally and accomplish a full, robust appearance.