When Is the Best Time to Trim Box Elder Bushes?

Timing

• Late winter or early spring might be the best times to prune most trees, but the box elder has different cutting requirements. Its free-flowing sap will bleed if you trim the tree just as the weather begins to warm. To prevent bleeding, trim your box elder after it fully leafs out in late spring or early summer. Don't remove more than one-quarter of your tree's live foliage at once, because it needs its leaves to turn sunlight into food. Losing too much foliage in one pruning could shock and weaken your box elder.

Purpose

• Box elders grow to about 30 feet with canopies that can spread to 40 feet. It's difficult to control the shape and size of such a fast-growing, large tree, so don't trim your box elder to maintain a specific height or canopy breadth. Rather, trim the tree to remove dead or dying branches and to thin crowded branches that rub together. For security and safety, trim your box elder if its branches block street signs or hide windows or doors to your home. Tree branches also must go if they hang over power lines, but for your safety, call a professional tree-care company to handle the job.

Trimming Tools

• You'll need several trimming tools to clean up your box elder. The most important tool is a pair of pruning shears to cut branches up to 3/4 inch in diameter. Consider buying a pair of lopping shears as well. Lopping shears work like pruning shears, but they have foot-long handles that give you leverage for trimming branches up to 1 1/2 inches around. To cut bigger branches of up to 4 inches in diameter, buy a razor-tooth pruning handsaw. Pole saws, which have long handles for reaching up into your tree, are an option for high branches, but they rarely result in clean trims because they're difficult to control. If you want to trim branches of more than 4 inches in diameter from your box elder, call a professional tree-care service. Its experts are practiced at using chain saws while standing on ladders.

Trimming Tips

• The best pruning job isn't obvious. Don't top your box elder by cutting the main trunk or large, high branches because you'll ruin the tree's natural shape and weaken branch structure. As your box elder grows, remove the lowest branches gradually, cutting off a few each season to raise the crown over time. Also prune branches that turn and grow back toward the tree. To trim a twig or smaller branch, cut it to within 1/4 inch of the branch it grew from. It's not necessary to apply a wound dressing to your box elder cuts.