Growing Roses Without Chemicals

Here is the basic approach which we use at Harlequin’s Gardens to grow hundreds of roses without using any pesticides or fungicides, and only using a few soft controls.

  1. Grow varieties of Roses that are strong and disease-resistant. In general, hybrid tea and floribunda roses are not so strong, cold-tolerant and well-adapted to Colorado as are many others. The best types of roses for us are the Canadian Roses, Modern Shrub roses, species or wild roses, some David Austin roses, and many of the heirloom varieties. The Boulder-Dushanbe Teahouse is a good example of a rose garden that requires very little pest-management because we are growing very well-adapted roses.
  2. Buy own-root rose plants. Roses that are grafted are more sensitive to cold and the entire plant has to grow from a single stem. This means that if some bug or disease should kill that stem, the entire plant will die and then the root stock will take over. Almost all hybrid tea and floribunda roses are sold grafted. Own-root plants will keep sending up more stems from the root and so renew themselves. They will have more flowers and will be tougher and longer lived. And if the plant dies to the ground or gets cut off or broken to the ground, the rose will send up new shoots from the root of the same plant you bought.
  3. Support the rose so it is strong and vital because weak plants attract pests and diseases, and because strong plants bloom more.
    1. roses like compost in their soil. Make a generous hole when planting and use a third to a half compost mixed well with the original soil. Beware of salty steer manure and fresh or little aged poultry manures. Well-composted manures are great for roses
    2. Use a good organic fertilizer twice a year, in May and September. Strong, chemical fertilizers force soft growth attractive to fungus diseases and sucking insects. They also kill beneficial mycorrhizae fungi. Organic fertilizers feed slowly over a long time.
    3. 4” of mulch over the root zone is good to hold moisture and to keep down the weeds and competition. It also makes feeding easier.
    4. Water only as much as necessary. Usually this means once a week for good performance. For some roses, once they have been established, water every two weeks. For some tough varieties, watering 5 times a year is good. Some will survive with very little water.
    5. If one big blooming a year is OK for you, the species roses, old mosses, gallicas, albas, found roses and some shrub roses can get along with no care and very little water.
  4. Learn to recognize the most common pests and diseases, and to learn when to use a control and when to leave things alone. The mere presence of a pest does not mean you have to do something. Leaving a few pests is leaving food for the beneficial insects and encourages their populations to build up in your garden. One of the big problems with using pesticides is that they kill all the beneficial insects. Observation is the most important tool; look at your roses closely. If something looks wrong or unhealthy, look under the leaves and/or get out the hand lens for a closer look. Whitney Cranshaw’s book Pests of the West is an excellent resource for identifying locally relevant problems. Just getting to know the insects in your garden enriches your gardening experience and helps you to feel less powerless.
  5. If the pest or disease level reaches a damaging level, then make adjustments in cultural practices and/or use non-toxic control. If a rose is in too much shade, you may have to move it. It you are overwatering, cut back. If you are under watering, water more. Or you may have to change from watering at night or in the afternoon to watering in the morning so the plant can dry out by nightfall. There are many good non-toxic controls:
    1. a strong blast of water can control aphids, spider mites and rose slugs
    2. horticultural oil acts by suffocation, not by poisoning and is very successful on many pests
    3. soap sprays act by dessication and are effective on soft-bodied pests, but should not be sprayed in bright sunlight and often must be repeated
    4. hot pepper and garlic sprays can be effective repellents
    5. neem has many formulations but is considered harmless and can be used for a control and repellant
    6. mostly little or no spraying
    1. If a certain rose keeps getting serious problems and needs too much spraying or maintenance, shovel prune it, and replace it with a rose that is better adapted to Colorado.
    2. Relax and enjoy the natural cycles and ups and downs of the garden; tolerate some imperfections. The strong varieties on their own roots will outlive most problems.
    3. Enjoy the roses, smell them, look at them closely, call them by name