Do Hemlocks Tolerate Severe Pruning?

Pruning Recommendations

• Hemlocks, yews, arborvitae and junipers are among the conifers that are tolerant of severe pruning, according to the University of Minnesota Extension. However, hemlocks have naturally symmetrical and well-maintained forms that do not require excessive thinning, pruning or shearing. You should remove only as much growth as is required to fix any defects or damaged areas.

Pruning Time

• Unlike conifers like pine that produce a major flush of new growth annually in spring, hemlocks continue to grow throughout the year. The trees can be pruned anytime of the year, including all through summer. It is, however, advisable to avoid pruning between late summer and early fall as this encourages the tree to produce new, succulent growth that becomes susceptible to winter damage.

Minimizing Pruning

• According to the University of Minnesota Extension, evergreens that are provided adequate cultural care, including an open site, rarely need to be pruned. Hemlocks are hardy in USDA zones 4 to 7 and are best adapted to the cooler, northern regions of the United States. The trees thrive in areas of full to partial sun and prefer a well-drained, moist soil with a pH ranging between 5 and 6.5.

Pruning Method

• When pruning the tree, don't cut into old wood as these areas rarely produce new growth. This tends to leave bare spots in the tree. A good method of pruning hemlock is to lightly shear the tree to remove the new growth slightly without drastically altering its natural form. Shearing helps to produce a more dense growth.