There are several courses of action to repair winter storm damage to deciduous shrubs. All of the suggestions offered in an earlier blog to repair damage to evergreen shrubs apply here as well. The level of complexity involved in some of these methods may make sense when involving key deciduous specimens in a landscape or a formally trimmed deciduous hedge but if that is not the case, it might make more sense to take the opportunity to rejuvenate damaged deciduous shrub.
The extent of rejuvenation would depend on the extent of damage. This procedure involves removing most or all old wood with loppers or a pruning saw close to the ground leaving six to twelve inch stubs to re-sprout. All damaged wood should also be removed at this time. Younger wood (four years and younger) may be left alone or trimmed by one third. If you don’t want the cuts to show, prune at the crotches. If you want a fuller, bushier plant, prune beyond the crotches leaving stubs from several inches to two feet long.
As buds break and growth resumes, you can top these new shoots removing the tips to encourage yet more branching. this method works on most deciduous flowering shrubs including lilac, roses, forsythia, spiraea, mock orange, azalea, burning bush, highbush blueberry and viburnum (and even many evergreen shrubs including azalea, boxwood, holly, rhododendron, yew, juniper and pyracantha).
Should too many new shoots develop, detracting from the natural form of the bush, remove some, flush with the branch from which they emerge.
Bushes can also be reshaped by driving stakes into the ground in locations you want branches to be and tying the closest branches to them. Check often to make certain the twine isn’t girdling the branches, adjusting as necessary. Stakes may be removed when branches thicken sufficiently to hold the desired shape without additional support.