For a gardener living in USDA hardiness zone 5, there are a lot of annual and perennial plants you can grow with success through cold winters. One shrub or bush that can grow well in zone 5 is the lilac, which lives for over a century when well cared for and in the right location. While lilacs require little maintenance, regular pruning can keep away some airborne diseases and ensure lush blooming year after year.
Wait for your lilac to finish blooming in mid to late spring, and for the flowers to die off. Use hand pruners to clip away the dried blooms just above the last set of leaves below the flower.
Look over the bush for old limbs that appear brittle or don't have leaves or flowers on them. Clip off these branches using your hand pruners, or garden loppers if the branch is thick, as far down as you can reach, cutting the branch at ground level if possible.
Cut back misshapen branches or smaller limbs that rub against a stronger limb where they originate or branch off from a larger branch.
Thin weaker branches of the lilac bush at ground level to leave behind at least three to five strong stalks on the bush to keep it healthy. These branches are already working on next year's flowers.
Maintain your lilac by deadheading the spent flowers each year, but allow three to five years to pass before pruning again. With each pruning after the initial pruning, try to remove a third of the plant, starting with the oldest stalks.