That is a question that we get frequently, and of course, the answer is complex, depending on the plant you have in question. If you are not sure about what your plant is, bring in a supple 6” or larger cutting and a picture of the entire plant.
KNOW BEFORE YOU CUT.
Why should you prune:
- To remove dead, broken, or diseased branches
- To control height, breath, and shape of the plant
- To promote flowers and/or fruit
We will attempt to cover the common shrubs and trees found in home landscapes as follows:
SPRING FLOWERING SHRUBS (deciduous) this group includes favorites like forsythia, bridal wreath Spirea, Hawthorne (flowering quince), and many others. Prune after flowering is finished in later spring. Generally, this group of shrubs flower on old wood.
SUMMER FLOWERING SHRUBS (deciduous) this group includes Weigela, summer flowering Spirea like ‘Anthony Waterer’ (did you see Spirea in the spring flowering group? Confusing?), Butterfly bush, and others. Prune after the last freeze and before new growth emerges. Generally, this group of shrubs flowers on new growth.
TRADITIONAL AZALEAS should be pruned after flowers have finished in spring. Do Not prune after July 4th and never prune more than 1/3 of the plant’s original size.
ENCORE AZALEAS which rebloom spring summer and fall should be pruned immediately after the first “show” of spring flowers. Pruning in the summer and fall will decrease the later flower “shows”.
HYDRANGEAS (deciduous) a large group with many diverse members all with different requirements, and really hard to generalize. I’ll hit the high spots, but it is very important to know what particular variety you have. Traditional French hydrangeas (mopheads and lace caps) do not appreciate pruning at all except to remove dead, broken, or diseased branches.
The #1 reason why they do not flower is that they are cut back. Oak leaf hydrangeas flower on old wood but may be pruned after flowering to control size. The re-flowering varieties like ‘endless summer’ bloom on old wood and new growth and should be considered as the traditional group. Limelight and its relatives flower on new growth and could be pruned after the last freeze and before new growth emerges. KNOW YOUR VARIETY BEFORE YOU PRUNE.
CAMELLIAS (evergreen) Prune after finished flowering. Remember that sasanquas and japonicas have different flowering times. Since sasanquas finish flowering in cold weather, it is suggested that pruning is done after the danger of the last freeze.
EVERGREEN SHRUBS prune these after the last freeze and before new growth. Never remove more than 1/3 height or width at a single time. Many in this family will “flush” with new growth several times a year, presenting the opportunity to prune more the once a year, but always before new growth and never more than 1/3. WARNING, if you want berries on hollies, prune only once in spring before the first new growth.
CRAPE MYRTLE (deciduous) the biggest source of pruning mistakes— CRAPE MURDER!!!
Thinning should be done in early spring after the last freeze and before new growth. February is ideal. Remove suckers at the base, crossing or rubbing branches, and branches growing inward towards the center of the plant. It is OK but unnecessary to remove old seed pods. All flowers are on new growth, pruning after new growth will delay the beginning of flowering. If you have to control the height of your crape myrtle by yearly topping, you have chosen the wrong variety for the location.
ROSES (deciduous) lots of subdivision here many with distinct requirements.
Traditional hybrid teas, grandifloras, and floribundas bloom on new wood and appreciate a severe mid-February pruning by thinning to 3-5 strong canes cut back to 12-18”. They will also respond to in-season pruning to remove spent flowers. Rose hips, crossing wood, etc rewarding you with a repeat flower show.
Climbers generally bloom on old wood and should be “thinned out” by removing crossing branches, dead, diseased, or broken branches one time in mid-February before new growth. Climbers that can re-flower appreciate continued grooming by removal of spent flower, rose hips, and crossing branches.
Knock Outs can be approached in two different ways.
(1) prune as a traditional rose before new growth in February. And follow up with continued grooming and size containment cutting as necessary through the growing season.
(2) after the first show of flowers, prune back to about 18” and thin out. This approach should eliminate additional in season pruning to contain size.
Drift roses- remove dead, diseased, or broken branches in mid-February.
GROUND COVERS vining type ground covers like Asian jasmine, English ivy, Vinca and others can be groomed as needed after the last freeze. The grassy-type ground cover like Mondo grass and the liriopes can have the old winter-worn foliage removed after the last freeze, But never cut these after new growth has started in spring.
SPRING FLOWERING TREES (deciduous) flowering on old wood, pruning should be done to remove damaged, broken, or diseased branches only. Best done while the tree is dormant. Branches damaged by spring/summer storms should be removed as soon after damage and be sure to seal any cuts wider than a nickel with pruning paint.
FRUIT TREES (deciduous) Generally major pruning to remove dead, broken or damaged branches should be done in late February, before blooming. However, corrective pruning can be done in season. Pruning to encourage fruit production should be done in dormancy to just before blooming. APPLES AND PEARS should be only pruned to remove poorly developed or damaged branches.
STONE FRUITS should be severely pruned by thinning out the interior of the branching structure, always cutting to an outside facing bud.
SHADE TREES (deciduous) really the only pruning that should be done to shade trees is to remove dead, diseased, or broken branches. Ideally done during the dormant season. However, storm-damaged trees should be attended to as soon as possible regardless of the season. Procedures for removal of damage on mature, valuable shade trees will be dictated by the scope of damage and may need to be addressed by a certified arborist or licensed tree surgeon.
CLOSING THOUGHTS — IN GENERAL THE WORST TIME TO PRUNE ANY WOODY PLANT IS FALL (SEPTEMBER-DECEMBER). PRUNING THEN WILL MAKE THE PLANT MORE SUSCEPTIBLE TO WINTER INJURY AND DECAY.