Can you tell me why my rose has withered. It is in a sunny south facing border in Toronto. I am not sure what kind of soil I have (acidic or otherwise) but it is good loam with proper drainage. I water by hand. This was just planted last year.
It would appear that with the exception of the rose bud and flower, the plant looks relatively healthy. However something is attacking the flower petals. There are a number of pests that like roses. They are:
- Rose Scale
- Rose Leafhopper
- Rose Slugs
- Specific Insects.
Unfortunately, the numerous insects and related pests that attack them can make growing them “interesting”, if not outright challenging. Based on the fact that the flower bud and petals seem to be the only thing attacked, it may be thrips or aphids.
Thrips are tiny, slender brownish insects that feed inside flower blossoms and buds. They quickly hide deep inside the flowers when they are disturbed. Silver flecks appear on petals as they scraped then their juices removed. Flowers become brown, tattered and flecked. Cutting off and discarding infected flowers is an effective and quick solution. Thrips prefer it hot and dry so increase watering so they get a good soak.
Aphids have several natural enemies, including parasitic wasps, ladybird beetles (ladybugs) and larvae, and green lacewing adults and larvae. Their natural enemies tend to keep aphid populations under control. Aphids can be hosed off with a strong stream of water directed above and below the leaves. Spraying with water should be repeated as frequently as needed, focusing in particular on new growth.
As with any plant, the first priority should be to provide the rose with the cultural conditions that it requires. A vigorously growing rose is much more likely to survive pest damage than a stressed plant.
Mound the base of your rose bushes with a good mulch for the winter to protect the graft from freeze/thaw cycles. Prune in the late spring when you see Forsythia blooming in your neighbourhood. Cut away any dead or diseased material and then shape rose by cutting back to desired shape & height. Water really well & less often will encourage roots to grow deep into the soil. Watering in the early morning will allow foliage to dry which will help minimize disease.
Compost or well rotted manure should be added to the soil around rose bushes. Since roses are a heavy feeder, a granular rose fertilizer, 6-12-6, can be used every four weeks up until mid-August. After mid-August stop feeding. Deadhead any finished flowers to encourage re-blooming.
Toronto Master Gardeners also have a great gardening guide for pruning roses that you might like to look at: