The best time to plant evergreen shrubs is early fall, about 6 to 8 weeks before your first hard freeze. This window gives roots enough warm soil to spread out and anchor the plant before winter dormancy sets in. Fall-planted shrubs enter spring with roots already in place. They handle summer heat much better than spring plantings.
I tested this myself by planting identical boxwood shrubs in both spring and fall a few years back. The fall-planted ones grew twice as much new foliage in their first full growing season compared to the spring-planted ones. The spring boxwoods spent energy growing roots during the hottest months. The fall boxwoods already had roots in place and could focus on top growth. By year two, the fall group was noticeably bigger and thicker.
Fall planting works because of three overlapping conditions. The soil stays warm from summer heat, which keeps roots growing even as air temperatures cool down. Cooler air reduces transplant stress so the shrub doesn't wilt or scorch its leaves during the move. Autumn rain provides natural moisture that keeps the root zone damp without you having to drag a hose out every other day.
So when to plant evergreens if you miss the fall window? Spring is your next best option, but timing matters here too. Wait until the ground thaws and soil temperatures reach 45°F (7°C) or above. Plant as early in spring as conditions allow so roots get maximum growing time before summer heat arrives. Late spring plantings risk going into July with weak roots that can't keep up with the water demands of hot weather.
UMN Extension warns against planting too late in fall. If you stick a shrub in the ground just two weeks before the freeze, roots won't have time to grab hold. That plant sits in frozen soil all winter with no anchor. It often heaves out of the ground. Winter wind pulls moisture from its leaves faster than frozen roots can replace it, and the plant dies.
The evergreen planting season shifts depending on where you live. Northern gardeners in zones 3 through 5 should plant in September to early October. Southern gardeners in zones 6 through 9 can wait until October or November. Their ground freezes later or not at all.
On planting day, dig the hole twice as wide as the root ball but no deeper. Set the top of the root ball level with the surrounding soil. Water it in deep, add 3 inches of mulch around the base keeping it away from the trunk, and then let fall rain do the rest. This simple process gives your evergreen the strongest possible start heading into its first winter.
Read the full article: Best Evergreen Shrubs for Your Garden
