Why do we prune roses?
There are several reasons we prune modern roses. Pruning allows us to shape roses to desirable heights and size characteristics to compliment our garden. We can prune to encourage the production of large, long-stemmed flowers from our hybrid teas or smaller but more abundant clusters from our floribundas.
Proper pruning also helps to create a healthy rose by removing the 3 –D's; dead, diseased and damaged canes. By thinning canes from the interior of the plant air circulation is increased. This decreases the likelihood of some common fungal ailments such as mildew. By removing dead or damaged canes we increase the overall well-being and beauty of our roses.
These general pruning recommendations are most applicable to hybrid tea, floribunda and grandiflora modern roses. Some of these varieties have special needs where consulting a rosarian at a garden center may be beneficial. The American Rose Society (www.ars.org) also has a consulting rosarian program available online. This resource allows you to find a rosarian in your area and correspond by email with your questions. Climbers, miniatures, ramblers and heirloom varieties have different pruning requirements and techniques.
When should we prune our roses?
There are guidelines, not rules, for when to prune your roses. Typically you should wait until after the last frost before pruning. This could be as early January in warm climates or as late as May in areas subject to a late frost.
Pruning a little late is not as tragic as cutting your plants back too early, causing them to suffer damage from a late winter freeze. In areas prone to severe winter winds you may need to partially prune large bushes back at the beginning of the season before covering for winter. This will reduce the chances of the entire plant being lost if several canes break off at the base of the plant.
What tools do I need?
Pruning roses does not require any specialized tools. The main cutting tool is a good pair of bypass pruning shears. Don't use anvil shears because in some cases they can cause damage to the plant. Bypass pruning shears make a cleaner cut which is beneficial when making precise cuts near a bud eye.
A pair of long handled bypass loppers is necessary for large canes. The long handles provide extra leverage necessary to cut thick old growth. In some cases a pruning saw may also be needed.
Protective clothing should be worn to avoid injury from thorns. A good pair of rose gloves will protect your hands and forearms from cuts. Wearing a long sleeved shirt and long pants is also recommended.
What do I cut?
Before you begin to prune think about the overall shape you are seeking for your roses. For many roses and gardens the classic “urn” shape is desired. This shape promotes an appealing, full shape. It also allows for an open center creating better air circulation within the bush.
Start by removing all dead branches and canes. Healthy growth will generally appear green or red where dead canes will generally turn gray or brown. As you cut into the canes if the pith is dry and brown continue cutting further down until you reach a green or cream color. Cut the canes low on the plant, as near to the base or bud union a possible. Also remove damaged canes and ones that cross or rub on other healthy growth.
Now we can start making the main pruning cuts on healthy stock. These cuts should be made about ¼” above a bud eye and at a 45 degree angle. The bud eye should be facing outward or in the desired direction of growth.
Remove all branches thinner that a pencil. With floribundas you can leave some smaller branches. You want branches of sufficient size to support your new spring growth. While pruning remember to keep the desired finished shape in mind.
How much do I prune?
The amount of pruning depends on the characteristics you desire of your rose during the blooming season. For more abundant blooms on smaller stems you may choose a lighter pruning. Leave most of the canes and only prune them back about 30%. You still need to remove very small branches and clean up the center of the plant.
Medium pruning general removes more foliage, leaving up to 8 – 10 well placed canes, fewer on hybrid tea roses. The canes should be reduced to 1/3 to ½ of their original height. This amount of pruning will generally work well for most healthy roses.
In some cases a heavy pruning is desired. You may have damage from a severe winter or a bush you cannot get under control with medium pruning. Make sure to cut back to wood to where the center or pith is healthy, living wood. Heavy pruning produces fewer but larger flowers or longer stems.
What else should I do?
You should also remove suckers, or rootstock shooting out of the ground from below the basal break. Spraying with dormant oil will help prevent some diseases. Make sure you clean up all of the clippings from the base of the plant. Throw these away and do not add them to your mulch or compost pile. Many rose pests and diseases survive in old rose debris.
What about harvesting and cutting dead flowers during the blooming season?
During the blooming season you may want to cut some of your fragrant blooms for your home or at least remove old, spent blooms. This process is called deadheading. Deadheading encourages the plant to re-bloom.
Cuts should be made similar to pruning cuts made on canes. Find a leaflet with five or more leaves and with a bud eye pointing in the desired direction of growth. Make your cut just above this location. Remove any petals or leaves that fall into the bush or on the ground.
Make sure the branches are large enough to support the new growth. Grandifloras and large hybrid teas will need larger branches to support the weight. By pruning in this manner during the season you will enjoy new blossoms throughout summer.
What if I don't prune correctly?
Fortunately for us roses are resilient. Experiment and see what type of pruning works best with your roses. As long as you keep your rose healthy you can prune again next year and try something different.