Post category: Roses
Greenflies can infest roses and cause reduced growth. Usually they are controlled by ladybirds or other natural agents but a heavy attack may need to be controlled with an insecticide, which are contained in most rose sprays.
Always keep roses free of weeds. A formal rose bed must be kept weed-free, neatly edged and tidy. Straighten and trim lawn edges in March. Remove all existing weeds.
Rose blackspot is inevitable in areas of high rainfall, especially in wet seasons. It causes black spots on the leaves, which then fall off. Some varieties are more susceptible than others but most are susceptible to some strains of the disease.
A spray of Multirose or Roseclear, or similar as the buds break in April, is essential. Spray again in May and June, and more often in a wet season, or a wet locality.
Rose mildew is generally only serious on ramblers. White chalk-like fungus grows on the leaves and stems. With susceptible varieties, spraying with Roseclear or Multirose will be necessary, starting in April. Mulching helps. Plant climbers instead of ramblers on walls.
Rose rust is an occasional problem but serious in some areas when it does occur. Rusty spots appear on the underside of the leaves. Spray with Dithane or Liquid Copper when the disease is first seen.
In March each year, bush roses should be given an application of 70 grams per square metre of general fertiliser, or rose fertiliser such as Goulding’s Rose Food, Rose Plus, Special Rose Fertiliser or Toprose.
Climbers, ramblers and shrub roses should get the same – especially in the early years after planting, and following periods of poor growth, or disease attack. Vigorous types may not need any fertiliser in some years.
A dressing of rotted manure, compost, shredded bark or peat, in April/May encourages good growth and conserves vital moisture, but too much manure can cause vigorous soft growth that is susceptible to leaf diseases. Do not use heavy organic mulches on heavy soil as it can leave the ground too wet and result in poor growth. Bush roses can be given a further 35 grams of rose fertilizer per bush, in early July, to encourage late flowering.
Pruning tall varieties growing in a windy situation in November reduces the possibility of root damage by wind rocking and leaves rose beds tidier over the winter. In a mild area, full pruning can be carried out. In colder districts, prune off the top half of tall varieties and complete pruning later.
First, remove all dead, damaged and diseased shoots. Then remove any weak, spindly shoots. Typically, between three and ten shoots will be left. Remove one in three of these from among the oldest, dark coloured shoots.
Shorten the remainder to between 15 – 30 centimetres. Large-flowered bushes should have their shoots pruned closer to 15 centimetres than 30 centimetres. Cluster-flowered bushes should be left closer to 30 centimetres than 15 centimetres. Prune cleanly just above an outward pointing bud.
The ‘head’ of a standard rose is pruned in the same way.
Note the difference between a climber and a rambler. Climbers are generally not pruned at ground level. Only the top framework is thinned out and the shoots that carried flowers pruned back to 10 centimetres. Weaker climbing varieties should not be pruned quite so much. Climbers are pruned in February or March.
Depending on variety, all ramblers throw some new shoots at, or close to, ground level each year. Whatever number of new shoots is produced, remove this number of old shoots, choosing the oldest to go. Over-long shoots can be shortened as necessary, or doubled back towards the centre of the plant.
For ramblers that produce very few new shoots at ground level, but produce some new growth further up on the older shoots, prune the older shoots back to one of these young shoots. Then, just shorten back the remaining shoots that have flowered. Ramblers are pruned in summer or autumn, whenever flowering finishes.
Tie in both climbers and ramblers after pruning. Completely overgrown climbers or ramblers can be cut back hard and re-trained. No pruning, other than light trimming, is needed for miniature roses.
Bush roses, standards and some shrubs and climbers are grafted. Suckers from the root-stock can appear and they will take over if not removed. Dig down below soil level and locate the source of the sucker. Cut it off. Replace the soil and firm it well to discourage further suckering. Suckers are easily recognised because they have more leaflets per leaf, carry more thorns, and grow vigorously.
Removing the faded flower heads from bush roses, standard roses and continous flowering climbers is worthwhile because it increases and prolongs flowering. Reach down past the faded flower bud and cut the stem at the first strong bud, contained in the axil of the leaf. This bud is usually located about 20-30 centimetres below the faded flower.
Roses are easy to establish but good planting will improve results. They can be planted at any time the leaves are off. November is the best month, but in areas of high rainfall and heavy soil, plant in March. Bare-root plants can be planted from October to March. Container-grown plants can be planted at any time, even mid-summer.
Rosa x odorata ‘Mutabilis’
Select a site and prepare the soil well. Dig holes 30 centimetres deep, 40 centimetres wide and 60 centimetres to 75 centimetres apart. The rows of holes can be staggered, to create a fuller flower effect.
Make up a planting mix of moist peat with a fistful of general fertiliser added per bucket. Mix a 5 centimetre layer of this into the soil at the bottom of each hole. Set up a line to get the rows of bushes straight and parallel to the edge of the bed.
Soak the roots in water before planting. Place the bush in the hole and spread the roots. Scatter some soil over the roots, and shake the plant slightly to settle it in. Plant to the depth of the graft union, where the shoots meet the root.
Firm the soil and fill the hole in two or three stages, firming each layer gently. Water each bush after planting and watch for signs of drought later on. The same planting technique applies to all types.
Shrub roses are spaced informally at 150 – 180 centimetres apart. Keep them about 150 centimetres away from competing shrubs or trees. Climbers are normally planted about 30 centimetres from a wall. Usually planted singly, they can be spaced 200 –300 centimetres apart, or from other wall climbers.
Tie the shoots of climbers into a horizontal position before they get tall. They generally do not flower for two or three years after planting. Tie in the new growth as it develops.
If an old rose bed is to be replanted with roses, the soil must be removed to a depth of 45 centimetres. Refill with new soil that has not grown roses before filled into a cardboard box. This procedure is necessary to avoid a problem called ‘rose replant disease’ that causes stunting and poor growth.
Old rose bushes can be transplanted quite easily. November is the best month.
Roses love sunshine; they grow best, flower most and suffer least from diseases if placed in a sunny position. The ancestors of today’s roses came from warm climates in Europe and Asia. They need all the sun they can get.
Roses do not like windy conditions. Provide shelter of trees, shrubs or hedges if the site is exposed, because wind and rain will destroy the blooms. But do not over-shelter rose plants because the movement of air helps to keep the foliage dry and therefore less vulnerable to disease.
Roses need full sunshine
Roses do not compete well with tree or hedge roots. Planted in an unfavourable situation, invariably the results will be disappointing.
Roses need deep, rich soil that drains well in winter but does not dry out in summer. It is worthwhile removing poor soil from the site for roses and replacing it from the vegetable garden or elsewhere, even buying in some good soil.
Work in plenty of organic material such as rotted manure or compost, or a 7.5 centimetre layer of peat. This improves drainage, retains moisture in summer, and promotes deep rooting. The soil should be completely free of perennial weeds.
Bush roses were bred for use in formal rose beds. The large-flowered bushes are best for formal rose beds near the house, and for cutting. Cluster-flowered bushes are ideal for beds of showy colour and could also be planted in groups at the front of a shrub border, or even singly. Cluster-flowered bushes are better suited to poor conditions, especially wet areas, because their flowers withstand rain better.
Rosa ‘Lili Marlene’
Choosing bush roses is a matter of personal taste, but there are do’s and don’ts. Choose either large-flowered bushes or cluster-flowered bushes. Do not mix them – the results can be very messy. Neither should varieties of large-flowered bushes be mixed in the same bed because mixed colours take from the effect of formal elegance.
The more showy cluster-flowered bushes can be mixed, but stick to two or three varieties – avoid the ‘fruit-salad’ effect. Try to match the varieties for height – use the taller ones to the back, or the middle of a bed, mixed border or island bed – and choose complementary colours. Research the variety and try to see it growing – visit St. Anne’s Rose Garden, Clontarf, Dublin, or a rose nursery during the flowering season.
Standard roses are used in the middle
Standard roses are used in the middle, or at the back of large rose beds, to add some height. They have long been used as specimens on their own, but less so nowadays. They could also be used in groups, or singly, in a shrub border behind low, non-competitive plants to give summer colour.
Being true shrubs, the shrub roses are best placed among other flowering and non-flowering shrubs. They bring colour to a shrub border in late spring and early summer. The shrub roses can also be planted as specimens on their own and some of them make good informal, secure hedges.
Climbing rose: Rosa ‘Seagull’
The climbing habit of growth of climbing and rambling roses makes them ideal for covering walls and unsightly large objects. They can also be grown on flowering garden trees to give more interest, or on an old tree stump, pillar or pergola.
Miniature roses have become very popular for patio and container growing. They can also be used on rockeries, and as house plants.
Bush roses, also called bedding roses, are upright bushes between 60 centimetres and 150 centimetres in height. Bush roses are grafted on to a vigorous rootstock at ground level by inserting a bud of the chosen variety. Bush roses are continuous flowering. They are often classified as hybrid teas – now correctly known as large-flowered roses – or floribundas – now called cluster-flowered roses.
Roses – the most popular flower
Shrub roses form a bushy shrub, generally between about 120 centimetres and 300 centimetres tall. Their growth habit is generally more vigorous and more ‘floppy’ than the bush roses and so they are wider.
There is a great range of shrub roses. Some are wild species, such as Rosa rugosa and Rosa rubrifolia; some are Old Roses, such as the moss rose and ‘Louise Odier’, and some are Modern Shrub Roses, such as ‘Nevada’ and ‘Frûhlingsgold’. Many shrub roses flower in a single flush. Some are continuous flowering.
Shrub rose: Rosa ‘Buff Beauty’
Climbing roses climb or scramble upwards if given support. They generally produce a mass of flowering shoots at the top of one or two main stems, which thicken with age. The stems are generally upright and stiff. Most climbing roses are continuous flowering and carry large flowers. Some are vigorous versions of bush roses.
Rambling roses also have a climbing habit but they are not as stiffly woody, and the stems are more flexible. The flowering shoots are carried on numerous stems that arise afresh from ground level each year, whereas climbers hardly ever produce new growth form ground level. Ramblers nearly all flower in a single flush of small flowers, mostly in early summer, some in late summer.
Miniature roses and patio are smaller than bush roses but very similar in all other respects. They range in height from 15 – 45 centimetres and are sometimes used as pot plants.