Answer: In general, container grown or ball and burlap shrubs that have been stored outdoors and are acclimated to the weather can be planted any time the ground is workable, meaning not frozen and not too muddy. Bare root plants should be planted as soon as possible while they are still dormant so they can wake up naturally with the season.
Overall, the earlier in the season you plant the better because the shrubs will have more time to become well rooted and established before the stressful heat of summer.
Midsummer is the least desirable time to plant because of the summer heat.
If possible, though, it is better to plant boxwoods and other evergreens in the spring. The best times to plant deciduous shrubs including burning bush would be in the early spring or early fall.
I hope this helps!
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