Gardeners whose main goal is super-healthy roses tend to plant landscape and groundcover roses these days. Two of the most popular are the Flower Carpet series and the Medilands.
Both Flower Carpet and Mediland types have the deep green, lustrous foliage that indicates disease-resistance and are relatively dwarf at three or four feet (90 cm x 1.2 m) tall and wide. They come in a variety of colours, double to semi-double forms and flower from late spring to frost. Most of them aren't fragrant.
Rugosa roses are taller, usually have strongly scented double or semi-double flowers and are pest and disease-resistant. Some, such as Hansa and Therese Bugnet, have large, decorative hips and colourful fall foliage.
But rugosas aren't quite as carefree as Flower Carpet and Mediland since Rugosas do sucker and are very thorny. Some are repeat-flowerers, but most produce masses of blooms in June and very little afterwards.
For many other roses, their health depends on their situation. The ideal spot is a on a sunny hillside in a not-too-rainy climate where there's constant air movement and a rich but well-drained clay loam. Finicky, disease-prone cultivars can live long, healthy lives in this situation.
Unfortunately, most of us live somewhere else - and all too often fungal diseases happen.
One of these is black (or brown) spots on rose leaves, which then fall off. Infection is reduced if you routinely pick these leaves from the plant and the ground and defoliate the whole plant in late fall.
At that time it helps if you remove the top inch (2.5 cm) of soil or mulch around the infected rose and replace it with new material. Lime sulphur sprays in winter also help. Because wet foliage encourages black spot, all watering of roses should happen early in the day and drench only the ground so that leaves dry.
The exception is when roses are infested with aphids. Blasting them off foliage with a strong stream of water is an easy cure, best done in morning when leaves have all day to dry.
Powdery mildew is another fungal disease that looks like white powder sprinkled over the leaves. It starts at the top of a rose bush during warm and very wet weather. But in any warm spell powdery mildew can be triggered by incautiously watering the rose foliage or watering the soil so vigorously that spores are flung up into the bush. This mildew can be treated organically in the same way as black spot.
Tiniest of all rose enemies are almost-invisible thrips, which deform flowers and streak them with brown lines. The flowers should be removed, but there will be surviving thrips that should be sprayed with insecticidal soap.
Caterpillars are another pest. The large ones should be left alone if possible because most will turn into butterflies or moths. The little green ones that hide in rolled-up leaves aren't hard to handpick.
Sometimes a strange and beautiful ball of red-tipped hairs will appear on a rose stalk. This is a gall that protects the larvae of a tiny pollinating wasp. These youngsters are too valuable to destroy.
Leaf-cutting bees that eat holes in rose leaves are also good pollinators. Their work is worth paying for by losing a few little bits of leaf.
Anne Marrison is happy to answer garden questions. Send them to her via [email protected].
