How can I care for my roses organically?
If you are planting a new rose garden then you have the opportunity to get a head start on the problem by planting relatively disease-resistant varieties. There are numerous cultivars to chose from. 'Knock Out' roses are a good choice as are David Austin English roses (although they are susceptible to fungal infection in humid climates). The 'Carefree' series are also to be recommended. Consult your local nursery for further suggestions.
When growing any kind of rose, following a simple set of rules will keep your plants healthy without resorting to chemical fertilizers and toxic sprays.
Roses need at least 6 hours of sun a day to thrive Also, don't plant them too close together as good air circulation will help to cut down on disease.
Rich soil with good drainage is best tor roses. A pH of between 6.0 and 6.8 is ideal for roses. Get your soil tested by your county extension service for pH and nutrients if you believe it has a problem. When preparing a new rose bed, incorporate about 3 inches of compost into the soil.
Watering and fertilizing.
Water deeply about once a week or mre often in dry spells. Water the soil not the plants. Fertilize regularly throughout the growing season with an organic fertilizer. Composted manure, alfalfa pellets or meal are excellent choices.
Place a 3 inch layer of mulch around the roses. Keep this level constant by re-applying mulch when necessary. This a very important step for growing healthy roses.
As a general rule of thumb, roses that flower only once in a season should be pruned right after flowering and roses that flower several times during the season should be pruned in late March or early April once the buds start to break (swell and green up): the adage is to prune your roses "when the forsythia blooms". For information on pruning roses by classification please refer to our guide Pruning Roses.
As an organic gardener you will want to avoid or limit the use of toxic chemicals to treat diseases. Choosing the correct rose varieties to grow and following the hints given above will reduce disease-related problems.
Roses are particularly susceptible to black spot, a fungal disease, however newer varieties of roses are relatively resistant to this disease. If you have a serious problem with black spot then consider spraying with organic controls, such a copper, sulfur, horticultural oil or neem.
Aphid infections can be reduced by spraying with a strong stream of water from a hose. Mites can be treated with an insecticidal soap with pyrethrin. Growing plants around your roses that attract beneficial insects is another step that you can take to reduce infection with insects. Many plant species can assume this role, e. g. yarrow (Achillea filipendulina), allium (Allium sp.), lavender (Lavendula sp), stonecrop (Sedum sp.), Rudbeckia fukgida, etc.
Don't expect to grow perfect roses. They will still be beautiful.
A useful book on this topic has been written by Peter E. Kukielski (the rose garden curator at the New York Botanical Garden) - Roses Without Chemicals, Timber Press, Portland, OR. (2015).
Courtesy of NYBG Plant Information Service