Pruning Old Roses
By Wal Johnston ©
Introduction
This is not a definitive work on pruning Heritage or Old Roses. It is issued for volunteers at the Victoria State Rose Garden who want to further their interest in the Heritage Border and the roses therein. It is an attempt to de-mystify the various Heritage Rose Families, give a brief description of each family's general appearance, and define a general method of pruning for each of the families.
General
When doing any pruning, keep in mind at all times the shape you want to develop or keep. If you want a rambler to cover a fence, then you will treat the rose quite differently from when you want a shrub shape. The size of the bush should be somewhat proportional to the size and number of the flowers or flower clusters. A new plant should be encouraged to promote new growth by removing the first season's flower buds. The plant will respond by producing more vegetative growth, both in canes and roots. An old plant that is not performing well can often have the same treatment applied with good results.
Generally, Old Roses should not be pruned until they have been in the ground for at least two years. However, some of the more rampant growers, such as Rosa gigantea or ‘Rambling Rector’ will require earlier treatment to keep them in control. Constantly remove dead or diseased wood, and where realistic, damaged wood. Damaged canes can be a source of dieback or disease, but plant shape may force you to retain some.
There are two schools of thought about when to prune once-flowering Heritage roses. One says to prune after flowering so that any sap flow will go into making more vegetative growth in the non- flowering period, thus giving more canes for next season's flowers. The other school says to prune when the rose is dormant so that buds are more easily identified and so that winter frosts will not damage new growth. It is of interest that there is another school
that suggests that Heritage roses should not be pruned at all, but left to grow "wild". Many of the Heritage families have spectacular displays of hips that are worthy of keeping. A delay in pruning becomes desirable to catch the display.
Species Roses Visual identification of a species rose is very difficult as there are so many varieties. Most have smaller than average leaves, small, often single flowers and frequently are rampant growers. On the brick signs (at the State Rose Garden) the name of a species rose is written in lower case with the letter ‘R’ in front of the name, standing for 'Rosa'.
Once Flowering Species Roses
Species roses produce their best flowers and hips on last year's strong growth. Imagine, in the wild, the herbivores "pruning" the wild roses and you will see that species roses can be harshly treated. After flowering, cut out dead, diseased, damaged, spindly and selected old (two years +) wood, keeping in mind the shape you want. Most American species roses (e.g. R. virginiana) are once flowering but their autumn toning and hip displays are worth delaying your pruning until late autumn or early winter. One oddity is R. sericea pteracantha, known for its translucent thorns. This should be cut to ground level to promote new growth for the early spring. .
Repeat Flowering Species Roses In late autumn or early winter, keeping in mind the shape you want, cut out dead, diseased, damaged, spindly and selected old (two years +) wood. Trim the remainder to attain the shape you want. Cut off the hips in winter plus about one third of the older wood. Shorten back new canes to tidy the plant.
Albas
Probably the hardiest class of Old Roses: flat double flowers, all spring flowering with taller lax-growing habit. Some have attractive hips. Usually these are very vigorous growers in southern Australia, although not so in the VSRG. After flowering, cut out some of the old wood to encourage new basal shoots. Trim to keep the shape you want. If you want the hip display, leave pruning until late autumn.
Bourbons Compact plants which flower spring to autumn on new wood. All double flat flowers and large green foliage. Can be trained onto pillars, espaliered or a spherical shape. Deadhead and light summer prune (i.e. cut off spent bud with stem as though it was going into a vase) to encourage repeat flowering. Peg down "fishing rods" to encourage blooms along the canes. In autumn, shape the bush by reducing the length of the fishing rod by half and cutting the growth back by about half. Remove dead, damaged and diseased wood and twiggy bits.
Centifolias Most centifolias are spring flowering. The larger growers in this class develop into lax open bushes with long "fishing rods". The leaves are large and rounded and the flowers are mainly pink, fragrant, multi-petalled and globular. The fishing rods can be pegged down to accommodate the shape required and to obtain more blooms. As centifolias have very few or poor hips, after flowering remove all dead, damaged, diseased and twiggy growth. Reduce the length of the fishing rods to about half.
Chinas
China roses tend to be low growing, small twiggy plants with recurrent blooms. (There are some exceptions such as ‘Mutabilis’) They would probably be the untidiest rose bushes. China roses resent being pruned, yet can be developed into a hedge with careful trimming. Prune by deadheading with an eye to the shape you want. It is better to remove entire old canes rather than removing twiggy growth, as the flowers tend to grow on such twigs. Remove all dead, diseased and damaged wood in winter.
Damasks Damask roses grow to a lax and a half, with long pointy grey-green leaves and plenty of thorns. Most damasks have pink, fragrant flowers and some set long thin hips. Damask roses are native to hot arid regions. In our temperate climate they tend to be very vigorous, requiring firm pruning to keep them in the shape you want. Many are repeat-flowering and will require constant deadheading to two or three buds below the spent flower. Winter prune to halve the growth made during the last season i.e. just above last season's pruning height. For once-flowering damasks, prune after the flowering period by removing selected old wood but still keeping in mind the shape you want to achieve.
Gallicas Gallicas are medium to low bushes with many small bristly thorns. Multi-petalled flowers are usually in clusters of two or three and are nearly always fragrant. Gallicas flower on laterals from two-year-old wood. Part of the Gallica charm is in the hips, so restrain yourself from deadheading. Most Gallicas are once-flowering anyway. In mid-summer cut back vegetative growth to flower height, forcing the sap into the flowering stems. Prune growth that has been bowed down with flowers.
In autumn prune to a dome shape; thin down the laterals to two or three buds. Selectively remove old wood that is no longer productive from the centre of the bush. On an older plant, plan to remove a quarter of the oldest shoots at the base. Remove dead, diseased and damaged wood.
Hybrid Musks Hybrid Musks are usually low-growing shrubs with long arching canes coming from the centre of the bush to form flower stalks. The leaves are dark green and plentiful and the small flowers clusters are on the end of the stalks or canes. They are repeat flowering and some have a fragrance. Having rambler in their heritage, Hybrid Musks can grow into huge bushes if left alone, or can be trained as climbers.
Deadhead through spring and summer to promote flowering by pruning the spent flower canes back to two or three buds from the main stem. Shape the bushes in autumn, retaining the hip display where feasible. In winter cut back long laterals to two or three buds from the main stem. Remove dead, damaged and diseased wood. Once a Hybrid Musk is established it needs little more than a summer trim to keep it in shape.
Hybrid Perpetuals Hybrid Perpetuals are tall, narrow, upright plants. The flowers are repeat, double and fragrant and grow on the top of the bush. Deadhead and light summer trim to encourage repeat flowering. The vigour of many Hybrid Perpetuals is not always reliable so resist heavy pruning. In winter shape the bush by reducing some of the older wood, which has been weighed down by flowers. Because of its upright nature, it is very difficult to obtain a good shape. Remove all dead, damaged and diseased wood and twiggy bits.
Moss Roses Moss roses are distinguishable from Centifolias by the moss-like growth on the buds and sepals. Bushes grow long canes that can be pegged down to increase flowering. The flowers are double, flat and fragrant. Once flowering: after flowering, reduce the length of the new fishing rod by half and the short new laterals back to two or three buds. Repeat-flowering: in winter prune quite hard to encourage compactness. Moss roses flower on two-year-old wood.
Noisettes
Noisettes are vigorous climbers with strong canes and plentiful foliage. Small usually double flowers are borne in clusters in early spring and tend to be singular as the season progresses. Noisettes will flower all year round. Prune in winter by removing all dead, damaged and diseased wood, and then thin out the bush by selectively removing some older less productive canes from the base in favour of new canes. The aim should be to replace every cane over a three year cycle. Reduce laterals from older canes, which are being kept, to two or three eyes. After pruning, the canes should be tied to the required position for shaping.
Rugosas
Leathery dark green leaves and thorns galore, with mainly single, fragrant blooms, rugosas will grow into solid blocky plants. Very suitable for hedges. Have a rest. Do nothing except shape the bushes. If a plant is old and straggly it can be heavily attacked in winter to create new basal growth.
Tea Roses Tea roses came in bush form or as climbers. In cold climates the Teas do not do well, but are quite vigorous in the VSRG. The bush forms grow up to a metre or more with a generally twiggy flower head. That is, the flowers tend to be in clusters on small twiggy growth, which tends to make them hang their heads. Flower shapes and colours cover the whole range. Most of the Teas are fragrant and have good foliage.
No matter when you prune Tea roses you will be sacrificing loads of blossoms. Leave them alone if you feel like it or prune them if you are feeling energetic. Either way they are forgiving. Such is the vigour of old Tea bushes that the spring flush produces masses of new canes literally covered with dozens of flowers and buds. By frequently cutting long stems of flowers in summer, you can avoid winter pruning. Judicious and gentle pruning will keep the bush within bounds wherever excessive size is liable to be a problem. Remove old twiggy growth and cut back long canes by a third to a half in late winter.
Ramblers Ramblers are easily distinguished from climbers by their thinner, more pliable canes. Almost without exception, ramblers are once flowering in spring although sometimes they may have an autumn flush. The majority of ramblers have their heritage from Rosa wichurana or Rosa multiflora. They mostly flower on wood produced in the previous season.
If you are growing a rambler to cover an unsightly fence, dead tree, or outhouse, resist any pruning. Cut off any nasties that would decapitate your friends as they go past, and take out any dead wood. About every third or fourth year, you could thin out the jungle to give new canes a chance. Cutting off a couple of the old unproductive canes at the base can do this. Cut them, walk away, and come back in two weeks or so when you can see the dead laterals in the mass of growth. Cut and pull until this is all removed.
When growing ramblers on arches, pillars or as a swag on a catenary, remember that the more horizontal you can make the canes, the more laterals which will develop and therefore the more flowers. Ramblers do not mind going downhill whereas a climber may strongly object and die back. They also have very flexible canes that can be easily trained and kept in shape. Wind the canes around supporting posts, tying them in to restrain them. It seems that a maximum of six major canes to each plant gives the best result.
In summer, when a mature plant has finished flowering, cut all the ties and lay everything down on the ground to unravel the canes. Reduce the number of major canes to six by cutting off older unproductive canes. Trim laterals back to three or so buds before rewinding the canes and tying them back in. Experience at the VSRG has shown that by pruning ramblers in summer, they will put on more vegetative growth before dormancy, thus giving more flower power next spring. It is usually necessary to give a shaping trim in autumn, but be aware that any major surgery at this time will be at the expense of flowers.
Climbing Roses
Climbers by their very nature want to reach for the sky and inevitably do not flower until they have reached the top. Most have rather thick canes, which resist bending, unlike ramblers. It is very difficult to study a rose or smell the perfume standing on a stepladder. So we must fool the plant to give us blooms at a lower altitude and yet have it reaching the top of a festoon, tripod or arch.
During the spring and summer, let the young climbing canes go as far up in the air as they can. Preferably the height reached should be the distance required when the cane is brought to the horizontal. Many climbing canes will not increase their length once they are trained to the horizontal. In autumn, take the long canes and gently bring them down towards the horizontal without stressing or breaking them and tie them at that angle. The canes should end up as close to the horizontal as you can get them, which may take several weeks of tying, then re-bending and re-tying to get them there.
Canes of climbers do not like going downhill, frequently suffering dieback in these attempts, so do not attempt to take them below the horizontal. In your home garden you can bring the canes down by tying an old soft drink bottle to the end of the cane. Add water to the bottle every couple of days to increase the weight until the cane gets to where you want it. Having tortured the canes into these new shapes stand back and watch laterals shoot up from almost every second bud. These laterals become the flower bearing shoots.
For recurrent climbers, deadhead the laterals fairly firmly (back to a plump bud three or four from the main cane) to give best displays of roses. In winter pruning, try to replace old non-productive canes with new young canes. For non-recurrent climbers, summer prune the laterals to the same level of two or three from the main cane, doing a shaping trim only, during winter. For best effects on a tripod or post, wind the canes around the tripod or post at about 45 degrees to the horizontal. This will entice the climber to throw laterals along the climbing cane and give roses at a lower level.
Printed with permission from Wal Johnston © 2007