What does “directing traffic” have to do with rose pruning? This is the phrase master rosarian Sue Streeper uses when she teaches her pruning workshop in Balboa Park. When we prune our roses, we guide the direction of their growth, their shape, height and size, the quality of their blooms and their health and vigor for the coming year.
We direct them to rest and then become productive.
Our plants naturally slow their growth and channel sugars to their roots as the days get shorter. They will tap into this stored energy for their initial stem and leaf growth in the new growing season. Pruning provides them with a rest and a restorative period.
To avoid setting our plants back, we must finish our pruning in San Diego by mid-February before our roses start to leaf out. We start at the base of the plant and prune out dead, damaged, diseased and old unproductive canes by sawing down at the base of the plant (known as the bud union on a grafted plant). This encourages and opens up space for the growth of basal breaks, which will become the new and more productive canes.
We direct the shape and size of the plant.
Roses are subject to a growth phenomenon called apical dominance. A plant hormone called auxin in the tip (apex) of the cane suppresses growth from lateral buds further down the cane. Removal of the tip through pruning allows the lateral buds to temporarily grow. This results in a fuller plant with more blooms on the canes.
Our next consideration in shaping our plant is to control disease. In order to minimize fungal problems we open up the center of the plant to air circulation and light. There is a bud eye at every leaflet set. We “direct traffic” by making our cuts one-quarter of an inch above a bud eye that is outward facing. This prompts the rose to grow in that outward direction and away from its center.
How much to prune? There are general guidelines on how much to prune, depending on the class of rose and the age of the plant. In San Diego, usually we do not prune more than one-third to one-half off our hybrid teas. With floribundas, polyanthas, shrub roses and minifloras and miniatures, we generally cut back only one-quarter of the height of the plant and we do not remove as many canes and as much growth as we do on the hybrid teas. All the canes on the bush do not have to be cut at the same height. Younger plants should be pruned very lightly.
Old garden roses that bloom only once need just a light grooming after their flowering has finished, and very little pruning in January other than the removal of old and dead growth.
Climbing roses are pruned very differently from other roses. The main canes are not pruned unless they are dead or damaged. Climbers bloom off lateral shoots, so this is a good time to train new, flexible canes horizontally as much as possible in order to encourage lateral growth. Your cuts are made at the third or fourth bud eye on each of the lateral shoots growing off the main canes.
We direct the quality and size of the blooms.
On hybrid teas, we want one large bloom per stem, so after the described basic clean-out of dead, damaged and twiggy growth, we generally get rid of stem-on-stems, also known as “doglegs,” and then we cut back to an outside bud eye on a cane that is thick enough to the desired future bloom.
We can leave some of these branching doglegs on floribundas and shrubs, but we do need to get to a stem diameter that will the quality of blooms or cluster of blooms we want. Next, we look for an outward-facing bud eye to make our pruning cut.
We direct their health.
We already cut out the dead, diseased and damaged canes, but if we notice that the pith in the center of an otherwise healthy-looking cane is brown, we keep pruning down the cane until we reach creamy white, healthy tissue. Pruning at the start of the new year has the added bonus of ridding the garden of last year’s problems. After pruning our roses, we strip all remaining leaves and we dispose of all canes and clippings to get rid of dormant spores of fungi and over-wintering pests.
If we decide to dormant spray with horticultural oil or insecticidal soap, this must be done immediately after pruning and before any bud eyes develop, as the spray can harm them.
Direction is best with the right tools.
Pruning is made a lot easier when we have the right tools. We need a sharp pair of by pruners, sturdy gauntlet gloves, a small pruning saw to make clean, flush cuts and a sharp pair of loppers to cut through thicker canes. It is a good idea to wear a long-sleeved shirt.
When we are finished, we need a rake to clean around the base of the roses to remove all leaves and clippings from the garden.
Hands-on direction
Pruning roses is best learned by watching the procedure and then practicing what you learned while being watched. Bring your gloves and pruners and attend the annual hands-on pruning workshop presented by consulting rosarians of the San Diego Rose Society at the Inez Grant Parker Memorial Rose Garden in Balboa Park. This year, the free event is on Saturday, Jan. 11, from 9:15 a.m. to noon.
Perwich is a member of the San Diego Rose Society, a Consulting Rosarian and a Master Gardener with UC Cooperative Extension.
