Rejuvenating Overgrown Shrubs
Renovation pruning is the answer to helping unhealthy shrubs that are overgrown, too tall, spread outside the bed, or lose their attractive shapes.
Pruning Gives Shrubs New Life
When a deciduous shrub becomes overgrown and you want to shorten it or shape it to make it more attractive, restoration pruning is the answer.
There are two approaches to rejuvenation pruning.
The first option is to cut an overgrown shrub back in one fell swoop. While the shrub tolerates severe pruning well, it may look unattractive for a season or two until it fills back in. Still, sometimes the all-at-once method is required.
The second option is to spread severe pruning out over several seasons. This gradual work keeps your landscape looking good and allows the shrub time to partially recover before its second or third sessions.
Most deciduous and broad-leaved evergreen shrubs respond well to either method of rejuvenation pruning.
If you chose the all-at-once approach, cut all the branches back to 6–12 inches (15–30 cm) above ground level at the beginning of the growing season.
The shrub typically grows back a fair amount of its lost foliage in the first year after pruning. By the third or fourth year, it will be full size again but have a lovely, compact shape.
From this point on, you can prune it lightly as needed with a combination of heading cuts and thinning cuts to maintain its height and shape.
The more gradual approach to rejuvenation calls for cutting a third of the branches to within 6–12 in. (15–30 cm) of the ground. This step is repeated each growing season for 3 years.
By the end of cycle, all the old wood will be removed and only healthy new growth will remain.
Special Situations
Restoration and rejuvenation pruning is best limited to deciduous shrubs, especially those that grow quickly and quickly become too tall or too wide. Broadleaf evergreens and coniferous shrubs require different approaches.
Avoid the rejuvenation pruning method for boxwoods, junipers, and most narrow-leaved evergreens.
When broadleaf or coniferous shrubs become overgrown, instead consider shaping them into a treelike form. Shaping reveals the sculptural qualities of these shrubs while giving them a neater look and creating space underneath for planting ground covers, flowers, and bulbs.
This is especially beautiful in a mixed flower-shrub-tree border, with plants in bloom throughout the entire season.
To create a multi-trunk tree from a multi-stemmed shrub, pick out three or four of the sturdier limbs. You’ll keep these as the faux “tree” trunks. Remove all the other low-growing branches, cutting them off flush with the ground or at their junctions.
Hawthorns, hollies, serviceberries, and wax myrtles are particularly attractive when pruned in this fashion.
Step-by-Step Instructions
Woody shrubs grow too large, suffer damage and disease, or become leggy or misshapen. When this occurs, it’s time for care and restoration.
Prune species that bloom on second-year wood right after they bloom. Rejuvenate other deciduous shrubs in the autumn after their leaves fall and they enter dormancy. Prune evergreen shrubs in spring.
Gather gloves, hedge shears, lopping shears, and an electric hedge trimming tool, then follow these steps:
How to Restore Overgrown Shrubs
Where there is dead or diseased wood, broken branches, signs of pests such as borers, or dripping sap, remove the affected limbs.
Remove any branches or laterals that cross the centerline of the shrub. Trim off suckers growing along the base of the shrub, along with any sprouts from the main trunk below the variety graft.
Note the basic outline of the shrub, trimming back all branches that extend more than 4 in. (10 cm) beyond the limits of its preferred profile and size.
If foliage at the shrub’s center is stunted, leafless, or yellowed, make cuts at trunk or stem to reduce the number of branches so that light penetrates to the center.
Reduce the number of branch laterals to open the shrub’s interior to light through its foliage canopy and improve air circulation, ending the shrub’s restoration.
Most roses bloom in repeat cycles called “flushes” throughout the gardening season, including the most popular classes: grandifloras, floribundas, hybrid teas, and many modern shrub and miniature roses.
They require annual pruning in fall to maintain vigor and control their form.
Climbers, pillar roses, and some species roses bloom once a season in spring. Prune these roses annually right after their bloom finishes and their flowers fade.
The goals of annual rose pruning are to maintain the form of the rose, remove any dead or diseased wood, cut out crossing branches, and leave only strong, healthy canes to sprout and produce blooms on new flowering wood.
Pruning Repeat-Blooming Roses
Repeat-blooming roses should be dormant before pruning. (Prune spring-blooming roses after their flowers fade.)
First, remove all dead canes and cut away any that are less than 3/8-in. (10-mm) in diameter.
Remove lateral branches that grow inward or cross through the center of the shrub. that cross the centerline of the shrub.
Trim off weak, outward-facing laterals, removing them at their junction with old-wood canes.
Cut off any diseased wood with discoloring, making additional cuts until the pith inside the cane is free of brown or black.
Top the remaining canes of the rose to 16–24 in. (40-60 cm) tall. The rose should now resemble an inverted bowl or vase, with several strong canes radiating from its central growth point or graft.
For standard or “tree” roses, prune the head of the flowering canes as you would a shrub rooted in soil, leaving a rounded, evenly spaced form.
Cut away any suckers growing from the understock below the variety graft that forms the tree’s “trunk,” or from the rootstock graft at the the rose tree’s base.
After pruning, a repeat-blooming rose is free of dead and dying wood, and it has a compact and symmetrical or mounding form. New growth will sprout and will double or triple the size of the pruned shrub, depending on variety.
