Roses are occasionally raised on their own roots but in the main are grafted (or budded). Those on their own roots include a few climbers, shrubs or speciesraised from cuttings, though most species are raised from seed; in all of these shoots coming from below ground-level can be allowed to remain, for none will be suckers.
REMOVAL OF SUCKERS
Most roses offered for sale are grafted, having a root system different from the aerial part of the plant. These roses may produce suckers and the gardener must be on the alert to deal with them. They usually arise from below ground-level, but this is not always the case with bushes that have been high planted so that the graft union is above-level. Equally, not all shoots rising from below ground-level need be suckers if bushes have been planted with their union below ground-level. Suckers on common bedding roses have smaller and more numerous leaflets than the rose variety. These leaflets are plain green, and either have no thorns or more numerous and smaller thorns. As there are several rootstocks in use for the commercial production of roses there is no one single type of sucker to watch for.
Whenever suckers are seen they should be removed; when they are small and young it is easier to do than when they are older and have become woody. They should not be cut off at ground-level because this encourages underground buds to grow away and the result is several suckers in place of one. To deal with them effectually first scrape away the soil and expose their point of origin, then take the sucker in a gloved hand and pull sharply downwards; this removes both the sucker and basal buds.
On standards, rub off any shoots which develop along the main stem and remove those that arise from below ground-level.
On species roses that are grafted it can be very difficult to detect suckers for there is a wider range of rootstocks used in their propagation and the suckers from some of these are very similar to the scion variety and difficult to identify. If at all possible, species roses should be purchased on their own roots.
When planted late in the season these can be pruned at planting time. All roses can be pruned when planting but it is more usual with autumn or late winter plantings to allow them time to establish,in early spring. All shoots are cut hard back: the weaker to two or three buds, the stronger to four or five.
Standard large-flowered bushes (hybrid teas) and cluster-flowered bushes (floribundas)
Prune less severely to seven or eight buds of the union.
Climbing hybrid teas and floribundas
Reduce to about half their original length. Too hard pruning of this group can result in their reversion to the bush types of which they are but climbing ‘sports’.
Cut to within 23 cm (9 in) of the ground, and weeping standards to the same distance, but from the graft union.
Shrub and species roses
Restricted to three main stems, the rest being removed completely. Those remaining are cut to about a third of their original length, all side shoots growing into the bush are removed and the rest cut to within two buds of the main stems.
PRUNING OF ESTABLISHED ROSES
Roses fall into two groups for pruning purposes: those flowering on current wood and those producingon growth of the previous year. The main sections within the first group are: hybrid teas, floribundas, polyanthas, grandiflora, hybrid perpetuals, hybrid musks, miniatures, china roses and the rugosa forms.
ROSES FLOWERING ON CURRENT GROWTH
The timing of the pruning of this group has long been controversial, every month from mid-autumn to late-spring having been recommended. Early spring is still the most popular period because it is claimed that shoots resulting are more likely to escape late frosts. But already at this time sap is rising and growth has begun, so some of the plant’s energy will have been wasted, and in some varieties stems bleed following late pruning. Shoots which develop after this pruning are strong and succulent and therefore very susceptible to severe damage should there happen to be any late frosts. By mid-spring, disease organisms are active and likely to invade such damaged tissue.
Autumn pruning has now been generally discontinued. In a mild autumn pruning can force bushes into growth which is killed in the winter. Pruning when the bushes are dormant is undoubtedly the best time, and this is usually mid- to late winter – though in some years growth never seems to cease completely. If, following early pruning, buds do start into growth the shoots develop very slowly and are hardy, acclimatising themselves as they grow and so are better able to withstand damage from late frosts – although they can be damaged by earlier severe weather.
TECHNIQUES AND PRINCIPLES OF PRUNING ROSES
Bedding roses can flower well and profusely if never pruned, but the framework becomes hard and woody and grows upward with each year. Eventually new growth diminishes, flowers are of poorer quality, the bush is cluttered with dead and dying wood, and disease becomes a problem. Light pruning has a somewhat similar result even if the upward development is slower and there is no clutter, but flowers, though numerous, will be of poor quality. Hard pruning produces a small bush, well supplied with young growth on which flowers are few but of the best quality.
As with all pruning, one first carries out the essential: cutting out all dead and damaged wood and any that shows signs of disease, thinning out crowded branches and removing shoots growing into the centre of the bush. Look at the bush and observe the position, amount and ages of the wood. One-year-old wood is green, two-year-old is brownish-green and wood older than three years is brown or black. From old wood will emerge shoots of one-year, two-year and even older wood. The aim should be to have a large percentage of one-year-old wood in the bush with most of this coming from, or near, ground-level.
Each year cut out some old wood, removing it to a point where young wood is breaking lower down, or cutting out completely any wood that has no younger wood, or very little, growing from it. At all times the aim should be to get rid of wood older than three years. On two-year-old wood, cut back to the lowest point at which young wood is developing, or if there is only terminal young growth, cut away about a third of the two-year wood.
With one-year wood, cut back weak growth to two or three buds and reduce strong shoots to a half or a third of their original length only. Strong-growing varieties should be pruned less severely than weaker ones.
When pruning, make the cut just above the bud horizontally or slightly sloping inwards. Cut always to an outward pointing bud. An exception is made on bushes growing on the outside of a bed, when a shoot resulting from an outside bud would be damaged by the mower or perhaps tear the clothes of a passer-by. Stems in such a position can be cut so the bud develops more or less parallel to the edge of the bed.
Small pruning cuts heal readily, but larger ones on three-year-old wood – say around 2.5 cm (1 in) in diameter – should really be sealed. Where a saw has been used, pare the cut surface with a knife before application. After winter pruning apply a proprietary bituminized sealant. This will seal the wound and help prevent the entry of pests and diseases through the wound.
Following the winter pruning, bushes grow away and by early summer are producing their first flowers. After these have faded, the bushes need to be dead-headed. This improves their appearance and diverts energy which would be used up in the production of fruit into the production of more flowers. Dead-heading does not consist of just removing the dead head, but of cutting down to where new growth is emerging, or removing about one-third of the new growth. This leads on to a good second flush and even to a third in some years.
Treatment of neglected roses
After reading so far you may have decided that something ought to be done about those roses which have never been pruned! Can they be brought back into order? Yes, it is possible to get them into good shape again provided that the hushes are not too old. It cannot, however, be done in one year; you cannot correct long-standing neglect overnight. Such corrective pruning is likely to be too severe a shock to the plant’s metabolism.
Firstly remove all dead, damaged and diseased wood. Open up the centre of the bush, cutting out crossing branches and thinning where crowded; cut back all young wood to within two or three buds of their base. Feed well and apply a combined spray. This should stimulate the bushes into growth and some shoots should be produced low down on the bush.
In the following winter there must be more concentrated effort. Cut out all old wood arising above young shoots produced low down. Remove completely at least one old stem at, or as near as possible to, the ground. Reduce at least one of the older shoots by half and cut back hard all young shoots on the bush.
Repeat the entire process the following year, cutting back all the time to where young growth is appearing low down on the bush. It will take at least three years to bring bushes back to normal but each year there should be an improvement in the amount of young wood produced and in the quality of the flowers. If there is no response after two years, the bushes are too old and should be lifted and discarded.
How not to prune!
Here are five common faulty cuts, all of which are likely to induce die-back in the shoot:
a) the cut is too far from the bud;
b) the slope is angled towards the bud;
c) the cut is too close to the bud;
d) a torn. Damaged cut will cause rotting, and
e) the slope is at too sharp an angle. Finally
f) is an acceptable cut in all respects.
ROSES FLOWERING ON ONE-YEAR-OLD WOOD
Climbing hybrid teas and floribundas
These produce new growth from ground-level which should be tipped and tied in. The strongest varieties do this reasonably freely and so all wood which has flowered can be removed completely. Unfortunately most kinds do not refurnish readily and some, perhaps all, of their growth which has flowered has to be retained. Along these flowering canes, all the flowering laterals are cut hard back to two buds. The oldest shoots should always be removed whenever enough new shoots have been produced.
These grow vigorously and produce an abundance of new shoots annually. All shoots, therefore, which have borne flowers are removed completely. In fact so strong are some varieties that far more stems are produced than are required. Whenever enough shoots have been selected and tied in so as to be well spaced, the remainder should be removed; do not be tempted to keep all just because they are strong and healthy. If these are growing over a tree, however, they can be allowed to grow unpruned except for the removal of dead wood. When climbing over a pergola, old stems are allowed to keep growing to provide a good covering, but all laterals which have flowered are cut hard back.
These are justgrafted on to a long stem. Following flowering, all stems which have borne flowers are removed completely.
Shrub and species roses
Can be left unpruned, but without attention they become thickets of tangled growth, their centres choked with blind, dead or diseased twigs. Annual pruning is desirable to open up the centre of the bush and thin out crowded shoots. Tipping of young shoots in the winter months helps to control the fungal disease. Roses with long arching branches can be shortened. Some species, (for example R. spinosissima), have a suckering habit and should have the oldest and weakest stems removed completely. One or two are grown for the winter effect of their stems, (e.g. R. omiensis pteracantha, which has large red translucent thorns on its young stems). To encourage strong stems, all are cut to ground-level in early spring.
SPECIAL TYPES OF PRUNING
Some of the more vigorous bushy kinds of roses can be used to make low hedges up to about 1.8 m (6 ft) in height. These are informal, producing flowers, and so are trimmed rather than clipped to strict formality. Amongst suitable floribundas is the variety ‘Queen Elizabeth’. Manymake good hedges, (e.g. the hybrid musks and ‘Nevada’) and of the many species suitable are R. rugosa and its hybrids and R. rubiginosa and its hybrid group, the ‘Penzance Briars’. Plant in well-prepared ground at 90-120 cm (3-4 ft) intervals and cut hard back to about 23 cm (9 in) to produce strong growth from ground-level. In the following winter, remove about half of the new wood, and so on each year until the hedge has reached its maximum height. Hedges flowering on current season’s growth are trimmed to shape in winter and any dead wood removed. When flowers are from the previous year’s growth, trim after flowering.