Basically in renewal pruning the entire shrub is pruned to within 4 to 6 inches inches from the ground.
Shrubs that can withstand this type of pruning include: barberry, forsythia, flowering quince, nine bark, privet, red twig dogwood, flowering almond, spirea, weigela, blue beard, potentilla, shrub roses St Johnswort, abelia and butterfly bush.
Renovation pruning on the other hand involves the removal of 1/3 of the oldest canes or branches at or near ground level. The following year another 1/3 is removed and new growth is reduced by approximately 1/2. On the third year the final 1/3 of the oldest branches or canes are removed. From this point forward prune annually to maintain a pleasing shape.
Shrubs that respond to this type of pruning include: rhododendron, forsythia, quince, lilac, barberry, rose of sharon, spirea, weigela, privet, bottlebrush buckeye.
Note: The best time to do either of these pruning techniques is in late winter to early spring, while the shrubs are still dormant. This is the case even for spring flowering shrubs that are usually pruned after flowering. Although pruning at this early time will cost you this year's bloom it will allow your shrub the most amount of time to recovery from its surgery before the harsh winter weather returns.
|Renewal Pruning Renovation Pruning|