Roses: The Queen of Flowers
Posted: June 13, 2011
Many of the roses commonly found at garden centers, such as hybrid teas, floribundas, and grandifloras, deserve that reputation, being prone to disease and insect problems, and do require the commitment to a regular pest control program to remain in good condition all summer. But even here, if you select carefully, there are some very disease-resistant varieties available.
If you find roses irresistible, as I do, but don’t want to fuss over them, look for modern shrub, old shrub, landscape, and species roses. These roses are often more disease resistant and will require little or no pest control, although they are not completely immune to insect or disease problems.
The drawback to some of the old-fashioned and species roses is that they have one main bloom period and do not continue blooming all summer, as the hybrid teas do. On the plus side, the flowers are often incredibly fragrant, something lacking in many modern varieties; and, to me, fragrance is a quintessential ingredient of roses.
Landscape roses such as the “Knockout” and “Drift” series are commonly available at garden centers, but many of the old shrub and species roses are only available from specialty rose growers through catalogs and the Internet.
One more point to keep in mind about roses of any type – “disease resistance” does not mean insect resistance. Even the most disease-resistant rose may get chomped on by Japanese beetles and roseslugs. The foliage of rugosa roses is very insect-resistant, but Japanese beetles will still devour the flowers. I usually tolerate the damage, knowing the beetles will be gone in several weeks, but the roses will continue to bloom sporadically into fall.
Here are some tips for keeping roses healthy during the growing season.
- Provide full sun – at least 6 hours daily. Morning sun is the most desirable for roses, as it helps to dry off rose foliage quickly. There are some roses that will grow in partial shade, such as “Zepherine Drouhin.”
- Grow in moist, well-drained, fertile soil, high in organic matter. Roses demand good drainage. They will tolerate clay soils, as long as it is well-drained. You can improve clay soil by working in a 2” layer of organic matter – compost, well-aged manure – each year. If your soil is poorly drained and you want to grow roses, consider creating raised beds for the plants. Roses prefer a pH of 6.2 to 6.8, although they are tolerant of a wider pH range from 5.5 to 7.0. Many of the species and old shrub roses, such as rugosas, will tolerate poorer soils than the hybrid teas.
- Space roses properly with room to grow and good air circulation. Most roses should be spaced at least 3-5’ apart, depending on their mature size. Good air circulation around the plants will help with disease problems. Most rose roots do not compete well with tree or shrub roots, or with turf.
- Use a 2-3” layer of organic mulch on the soil around the base of rose plants. Applying organic mulch – such as bark, wood chips, shredded leaves, wood chips, or cocoa bean hulls – around roses helps control weeds, conserve soil moisture, and moderate soil temperatures. Put down fresh mulch in the spring, because one of the places black spot disease overwinters is in leaf debris that falls into the mulch.
- Water thoroughly but keep foliage as dry as possible. Shrub, landscape, and species roses will be more drought-tolerant once established than hybrid teas, grandifloras, and floribundas. During dry weather, water roses about every 7 to 10 days. Water slowly but deeply. When watering roses, apply the water directly to the soil around the base of the plant. Avoid overhead watering, and water in the early morning. Wet foliage increases the risk of disease problems.
- Fertilizing. Roses should be fertilized to encourage vigorous growth and abundant blooms. You may use organic fertilizers such as compost, manure, alfalfa meal, or cottonseed meal, or you may use an all-purpose 10-10-10 fertilizer. This should be applied at the rate of one pound of fertilizer per 100 square feet or ½ to 1 cup per plant. Shrub, landscape, and species roses should be fertilized once in the early spring. Hybrid teas should be fertilized three times a year: in early spring after pruning, during the first bloom, and in mid-July. To discourage late-season growth, do not fertilize after the end of July. Late-season, succulent growth may not harden off properly before winter and will be susceptible to winter injury.
- Deadheading. Deadheading is the removal of old flowers to conserve energy and encourage new blooms. This should be done at least once a week, although some of the landscape and shrub roses do not require deadheading to continue blooming. Newly-planted roses should have spent flowers removed just above the uppermost three-leaflet leaf. Established roses can be cut back to just above a five-leaflet leaf. Stop deadheading roses in late summer. This allows the development of rose hips, which promotes hardening of plants for the winter months.