Pruning Roses: A Toronto Master Gardeners Guide

Rosa ‘Floral Fairytale’ is a compact rose that requires only light pruning. Photo: Helen Battersby

This gardening guide provides introductory information about when and how to prune roses. The appropriate pruning techniques depend on the type of rose and the growth pattern desired. Pruning roses correctly should result in a well formed, vigorous plant that blooms more prolifically and is more inclined to resist disease and pest infestations. For the best ongoing results, roses should be planted with their crown union 3” – 4” below ground level.

Why Prune

Pruning is done for many reasons. Pruning removes potential leaf surface from the rose plant and, as a result, will direct growth in the plant. Pruning is done to remove diseased, dead or damaged wood and crossed canes. Pruning can also be used to shape the rose (formative pruning), to thin the plant for better air circulation, or to reduce its size (restrictive pruning). Pruning will result in a more vigorous plant as old wood is removed (renewal pruning) and will also encourage the production of larger or more abundant flowers.

When to Prune

Roses should be pruned in early spring at the end of the dormant season. In Toronto this is usually in April or May, just before new growth begins and as the buds begin to swell. Wait until the danger of a hard frost is past or newly pruned tips may be killed. Prune climbers and ramblers lightly after flowering.

How To Prune

General Pruning Principles

As a general rule, if a plant is healthy and able to withstand hard pruning, the harder the shoots are pruned the more vigorously the new canes will grow. Light pruning promotes less vigorous and more limited new growth.

Use strong, sharp pruning shears to make a clean cut with no ragged edges. Cut no more than 1/4 inch above an outside-facing eye or growth bud. Angle the cut so that it slopes back slightly and away from the bud to allow moisture to drain away. These rules apply to all roses except those being trained to grow along a support and prostrate types.

When removing a complete stem, cut as close as possible to the parent stem, then trim the stump flush with the stem, using a sharp knife. Cut thick stems with loppers for a good, clean cut. For old hardwood use a narrow-bladed pruning saw.

When thinning out wood cut back to the next branch. This creates a more natural appearance. It also avoids numerous stubs, which give the plant a butchered look and invite disease.

Newly Planted Roses

Prune newly planted roses immediately, unless they are planted in the fall. If planted in fall wait until spring. This initial pruning should remove any dead, broken or weak wood and any stems that rub or cross. Beyond this, the initial pruning should be matched to the type of rose, as follows:

  • Hybrid tea roses and grandifloras – prune hard, four inches from the ground;
  • Floribundas – prune five to six inches from the ground;
  • Species roses – prune moderately, since they bloom on wood produced in the previous season;
  • Climbers, ramblers, shrub roses – prume moderately;
  • Polyanthas, miniatures – cut back polyanthas by one-third; miniatures should be pruned to two inches off the ground, except for climbing miniature roses which should be pruned the same way as climbing roses.
Suckering

A rose can be either grown on its own roots or budded or grafted onto a rootstock. If the rose is grafted, the suckers that grow from below the bud union will be quite different from the rose growing above the graft. Suckers should be removed as soon as they are noticed. Remove them from the point where they emerge. Tear or rip them from the main stem rather than cutting. Burying the graft union 3” – 4” below the surface will help minimize suckering problems.

Ongoing Pruning of Roses

As with the initial pruning, appropriate annual rose pruning depends on the type of rose. Each spring, any dead, broken or weak stems should be removed. As well, any stems that are rubbing or crossing should be pruned out. Beyond this basic maintenance pruning, pruning based on rose type is as follows:

Hybrid Perpetuals and Hybrid Teas

For moderate garden display, cut back the top of all stems by about 1/3 in the spring. Larger, but fewer, flowers can be produced with harder pruning, as far back as three buds above the base of the stem. Perpetual hybrids bloom best on one-year-old wood. Each spring remove some three- to four-year-old wood at soil level and trim new growth back to three to four feet. Light pruning should be done when flowers are cut for indoor use or when deadheading.

Floribundas and Grandifloras

The top of each stem should be cut back by 1/3 each year in the spring. You can hard prune to three buds above the base of the stem. Floribundas and grandifloras develop new shoots more freely than do hybrid teas, so somewhat less pruning is needed.

Climbing Roses

Don’t delay pruning climbing roses since they need yearly attention for optimal growth and flower display. Some climbers such as ‘New Dawn’ naturally produce more new canes than do others and will require heavier pruning. In the early spring only undertake basic maintenance pruning. As soon as the flowers have faded in the summer, cut back the laterals on which they were borne to within two or three buds of the main canes. New leaders, which are noticeably larger in diameter than the laterals, will often grow higher up on old canes. Cut back these canes to just above the new growth. Tips of laterals that are too long can be pruned back at any time. When new leaders are supple they need to be directed and tied to supports as they develop.

Ramblers

Ramblers develop long flexible canes from the base of the plant. These canes do not flower until their second year of growth. Prune soon after they flower. For each new cane remove an old one at ground level. If many new ones come up remove the weaker ones. Some varieties produce new canes above the base and the old one can only be cut back to that point. If there is little new basal growth, retain the strongest old canes, and cut the side shoots back to two or three buds in early spring. Ramblers are best trained on supports that allow the air to move freely. Prune weeping standards (ramblers budded onto an upright stem) like ramblers.

Shrub Roses

This group includes Rosa centifolia, R. gallica, R. moyesii, R. multiflora, and R. rugosa along with hybrids of these species such as the Explorer series of roses and roses such as the David Austin roses. They all have a bushy, spreading growth habit. Many of them make excellent dense hedges that ultimately require minimal pruning. They flower best on short laterals produced each season on the older wood. Consequently, they are usually pruned only lightly in early spring.

Miniatures and Polyanthas

These roses need little pruning other than trimming the tips back, thinning and removing weak shoots. In summer prune any extra tall shoots to maintain the plant’s symmetry.

Tree and Standard Roses

Prune these types of roses hard and shape to provide a rounded head. Because these roses have been grafted onto tall rootstock, their grafts usually require winter protection. This can be achieved by tipping the plant over and covering the graft area with soil for the winter.

Pruning Rose Hedges

Shrub roses lend themselves well to an informal hedge. Match the growth habit of the selected shrub rose to the desired size and shape of the hedge. The first few years are critical when developing a rose hedge. Annual pruning should remove growth beyond the imaginary planes of the hedge’s sides and top. It may be desirable to prune after the first flush of flowering to remove wayward branches. Keep the base of the hedge wider than the top so adequate light is available to the entire surface of the hedge.

Considerations

Plant a rose that suits the space. If you don’t you will constantly be working against the natural growth pattern of the plant, creating more work than necessary, and your results will never be as satisfying.

Be on the lookout for problems such as rose galls (swellings formed by small insects that lay their eggs in the stems). Hatched larvae feed on the inside of the stem causing it to swell. Cut out any unnatural swellings as soon as they are noticed. Cankers should also be cut out as soon as noticed.

Also, when pruning, if any of the cut canes have a hollow stem you may have stem boring sawfly larvae in the rose. The most effective way to deal with this pest is to remove each affected stem down to a point where the pith is solid and white. The canes that have been removed should be destroyed, not composted.

In general, it is better to destroy rose canes rather to compost them — climbers in particular have very sharp thorns. Diseased plant material should never be composted.

Always prune with clean, sharp tools.

References

Brickell, Christopher, Trevor Cole, Judith D. Zuk (Eds). Reader’s Digest A-Z Encyclopedia of Garden Plants. Montreal, Canada: Association (Canada) Ltd., 1997

Date revised: March 11, 2006

For printable version, click:  Pruning Roses – A Toronto Master Gardeners Guide

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