1. Proper plant selection and good gardening. Select varieties known to be healthy-growing roses for your area. Plan the garden so that roses receive at least six to eight hours of sun a day -- the more sun the better. Plant your roses so that they do not crowd one another, providing optimum air circulation around and through the shrubs. This will lessen stagnant pockets that become an ideal home for disease and insects while also making it easier to keep weeds down. Feed roses with a balanced rose fertilizer on a regular schedule, making sure not to apply too much nitrogen. When overused, this essential fertilizer component causes succulent growth (which is more attractive to insects and more susceptible to disease).
2. Observation. Survey the level of trouble in your garden while performing your regular chores. Check for insects and disease as you prune or water. If a particular rose isn't strong and is prone to attack to the point of hardship, remove it. Plant a more vigorous bush in its place.
3. Natural intervention. If a problem arises, turn first to natural and nonchemical intervention. Use water to knock off aphids, or rinse off the underside of rose foliage to remove mites. Clean foliage is healthy foliage. A few products that use biocompatible fungicidal components such as sodium and potassium bicarbonates are proving to be effective in controlling the major foliar disease in the rose family. A good response can be to release predatory insects into your garden to help get pests under control.
4. Low-toxicity intervention. In some circumstances, it may be necessary to resort to slightly more toxic solutions. Products such as horticultural soap that are modified to control insects or diseases are short-term solutions. Horticultural oils, used when the weather permits (temperatures must not be higher than 80 degrees F, or foliage damage will occur), are quite effective against some of the more stubborn pests and diseases.
5. Chemical intervention. For some gardeners, chemical intervention is a perfectly acceptable last resort. But there are wise choices even here. Products such as neem oil or phyrethrins are effective short-term insecticides and can be used with relative safety. They will kill insect allies, however, so don't use them if you have gone to the expense of releasing predatory insects, such as lady bugs. Read the labels, follow the instructions to the letter, and use chemical intervention on a selective basis. Treat the problem, not the garden. If one bush has an infestation of spider mites, then spray only the affected plant.
Download our helpful chart on disease-resistant flowers. (Downloading requires Adobe Acrobat software.)