Rose

Light and exposure

The rose wants full sun, at least six hours a day. That is non-negotiable: less light, and you harvest few flowers and plenty of disease. Reserve it the most open, sunniest spot in the garden, away from the shade cast by a wall or a large tree.

The other factor, often forgotten, is air circulation. A rose planted in a confined corner, between two hedges or squeezed against a wall, keeps its foliage damp and catches everything. Leave space between plants so the wind dries the leaves after rain. In a damp climate, an airy rose is a healthy rose.

Watering

The rose likes soil that stays cool deep down. Water generously and spaced out rather than a little every day: a good bucketful once or twice a week in summer is better than a daily trickle. The water must reach the deep roots, which is what makes the plant self-sufficient and resistant to dry spells.

Always water at the base, never on the foliage, and preferably in the morning. Leaves wet in the evening stay damp all night and invite black spot and powdery mildew. Mulch at the base keeps in moisture, limits watering and stops rain from splashing spores up from the soil onto the lower leaves.

Soil and repotting

The rose requires deep, rich soil that is cool but well drained. It hates standing water as much as drought. Clayey, heavy soils hold water: lighten them at planting with mature compost and potting soil so the roots can breathe.

The ideal planting is bare-rooted, in autumn, once the plant is dormant and while the soil is still warm: the rose settles in all winter and starts strongly in spring. Dig a wide hole, dip the roots in a slurry, and bury the graft point three or four centimetres below the surface. In a container, planting remains possible almost all year outside frost and great heat. Autumn keeps the advantage wherever the ground does not freeze deeply; under a severe winter, plant instead as winter ends.

Temperature and humidity

On the cold side, little to worry about: the classic garden varieties are hardy down to about -20 °C and overwinter outdoors without protection. Winter frosts do not kill them, they are part of their cycle. The sensitive point is the graft union: young plantings, and every grafted rose wherever the thermometer drops below -15 °C, appreciate a mound of soil at the base to get through winter.

The real issue is not temperature but air humidity. A mild, rainy spring and summer keep a damp atmosphere around the foliage, and that is exactly what black spot and powdery mildew love. Anything that dries the leaves, full sun and airflow, works in your favour.

Pruning and upkeep

The main pruning is done in late winter, when the forsythia flowers and the hard frosts are over. For repeat-flowering roses, bush roses, hybrid teas and floribundas, cut back to three to five buds above an outward-facing eye, with a clean, slightly slanted cut. Remove dead wood, spindly branches and those crossing towards the centre to open the clump to light and air.

Non-repeat roses, which flower only once, are pruned on the contrary just after their flowering, not in late winter, otherwise you cut off next year’s flowers. During the season, remove the faded flowers of repeat-flowering roses above the first full leaf: this triggers new growth and extends flowering into autumn.

Pests and diseases

Foliage diseases are the rose’s number one battle in a damp climate. Black spot disease, marssonina, is the most common: rounded black spots appear on the leaves, which yellow then fall, and a rose that goes bare exhausts itself. Next comes powdery mildew, a white powdery coating on the young shoots and buds, favoured by cool nights and mild days. Rust, for its part, is spotted by its small orange pustules under the leaves.

The best defence is not treatment but the initial choice: plant disease-resistant varieties, recognisable by the ADR label. Then, provide airflow, never wet the foliage, and carefully gather up the diseased leaves fallen to the ground, where the spores overwinter to reinfect in spring. As for pests, aphids colonise the young shoots from spring onward: a jet of water or ladybirds often deal with them without any product.

Propagation

Cuttings are the most accessible method to propagate a rose, especially shrubs and old roses. In late summer, take a section of the season’s stem, about twenty centimetres, below an eye. Remove the lower leaves, plant the cutting two-thirds deep in a mix of soil and sand, in a sheltered spot, and keep it cool. Rooting takes several months and is checked the following spring.

Grafting onto a wild rose is the nurseryman’s technique for hybrid teas and modern varieties, but it requires skill and a rootstock: reserve it for patient gardeners. Sowing, for its part, does not faithfully reproduce horticultural varieties and serves mainly to create new crosses, not to propagate a rose you love.

Month-by-month care calendar

Green Hub tips

• The real anti-disease protection happens at the point of purchase: take a resistant variety, ADR label, rather than chasing treatments all season.
• Full sun and air around the foliage: these two reflexes dry the leaves after rain and cut the ground from under black spot and powdery mildew.
• Prune at the forsythia. When it flowers, the hard frosts are over and it is the right moment to cut back repeat-flowering roses.
• Gather up and throw away the spotted leaves fallen to the ground: that is where the disease overwinters to reinfect the rose the following spring.