How to Grow a Rose
by Mary Jasch
Do you, like me, buy a rose just because it’s gorgeous and you want it? I know, isn’t that reason enough? And maybe you’ve heard that Hybrid Ts are difficult and disease-prone, requiring constant spraying and you’ve always heard the terms shrub roses, floribunda, grandiflora, polyantha, Musk, Damask, Old Garden Roses but never really knew what they meant? Jeff Van Pelt, garden consultant, rose expert and lecturer, explains it all here.
We’re going back to basics here, then delve into the fine points with tons of tips from Van Pelt. First, all roses are shrubs, despite the “Shrub Rose” class. As they age, older canes become woody like any other shrub with a bark-like texture which buds find difficult to break through. Roses have many classes and not all are described here.
Hybrid T: Bred for cutting with one flower on a classic, single stem, it is the tallest type of Modern Rose. Mr. Lincoln and the single-petaled Mrs. Oakley Fisher are examples. La France was deemed the first Hybrid T in 1867. “They are artificial and require a lot of maintenance and are not disease-resistant or winter hardy," says Van Pelt who recommends old standards such as Chrysler Imperial and Tiffany and staying away from white. If you want white, get grandiflora, he says, and if you want Peace, plant the more vigorous and disease-resistant climber. In spring, prune Hybrid Ts down to eight inches, though you may have to go higher on woody canes to find a bud.
Grandiflora: Of medium height, this Modern Rose has three or four T-like flowers on each stem. Older canes tend to get woody and form fewer buds, and may need to be pruned higher up the cane into the green to find a bud. “Every once in a while you hope for a hard winter to kill the canes low to the ground,” Van Pelt says of having to prune maybe two or three feet high. If the bush has a lot of old canes, cut one to the ground and let it send up new canes. See how it responds. Mount Shasta and Queen Elizabeth grow to eight feet. “You’ll want a hard winter to bring them lower to the ground.”
Floribunda: These shrubby roses are the most disease-resistant and shortest of the Moderns with multiple tresses of flowers on each stem. The flowers are smaller than Hybrid Ts and Grandifloras. A few recommended Floribundas: Cherry Parfait, Brass Band that glows on misty days, and Poulson’s Pearl, a gorgeous soft pink. September is unstable; its bicolor flowers appear in any red and white combination and Betty Prior is a black spot magnet.
Shrub Rose: A catchall for new varieties that don’t fit other classes, shrub roses require less maintenance, less fertilizer, less pruning, less spraying. “They tend to live on their own and keep on flowering,” says Van Pelt. Knockouts do well but Rainbow doesn’t re-bloom. Knockouts grow to eight feet so cut them down to eight inches every year so they grow many new canes. This induces more flowers because they bloom on new wood. Knockout grows four feet a season and is susceptible to rose rosette. Prune The Fairy with a hedge trimmer. Prune the Home Run Series ‘no spray roses’ to 12 inches and Carefree Delight to four. Home Run is great looking, winter hardy and disease-resistant. Carefree Sunshine grows like multiflora. The Romantica series are black spot magnets.
Miniature: This rose grows to two feet. Cover plants in winter that are close to a hardscape to protect it from sun and heat. Hardscapes are warmer than air and remain so when the sun goes down. The higher temperature dessicates branches and cells. Cover them with evergreen boughs. Prune with a hedge trimmer.
Some Special Roses: Though R. spinosissum only blooms once, its small leaves and fine structure fit well in the back of a garden. This disease-resistant, low maintenance plant grows five feet tall. Deer don’t like it because its little leaves don’t cover the thorns. Canary Bird is a good forsythia substitute at eight feet tall and wide. Nothing touches it—neither bug nor deer. Rugosa species with crinkly, hairy leaves generally do fine. Pavement series will cover an embankment in three years.
A winter’s snowfall will kill Hybrid Ts down to the snowline, Van Pelt says, or if it’s been really cold, they might die to the ground. If roses start to come out of dormancy, a late snow will also kill them to the ground. The plant can’t go back into dormancy (protection mode) and new growth will die.
Look for brown or black spots on the canes now. Black = dead. Brown = may be dying. Cut off all black and brown canes, to the ground if necessary. If you cut to the ground, mark the spot.
Sunken areas of black or brown spots are most likely fungus says Van Pelt. When pruning, dip clippers in a 10% Clorox solution. Downy mildew likes cool, wet weather –and overhead sprinklers. It shows as purplish-reddish spots with wavy edges along leaf margins, veins, mid-ribs and sometimes inside as yellow spots with purplish-reddish edges.
Black spot fungus likes it hot and wet and begins to appear in June as a dot, or circle.
Modern hybrids are resistant to rose rosette. R. multiflora is not. Wingless aphids carry the virus. If your rose has it, get rid of the entire plant.
If you see holes in rose leaves, the bugs are already gone. Do not use systemic pesticides like Roundup and Merit (banned in Europe). They get into the groundwater and affect people.
Year-round Rose Care
Late March/early April:
1. Remove all mulch and old leaves from and within the plant.
2. Prune off dead and diseased canes and crossing branches.
3. Trim canes to outward-facing buds at heights stated above. Cut ¼-inch above the bud.
- Do a secondary pruning. Take out new growth from the plant’s center to keep disease down.
- If disease gets ahead of you, cut off the flowers.
- Keep leaves on the plant to produce energy.
End of September:
- Stop deadheading roses. Let them produce seed and go into dormancy.
- Top them to 3 feet and remove leaves. (Leaves hold disease inoculant.)
- Put minis and tree roses in a protective spot (unheated garage or dig a trench and bury it) and keep moist.
- Don’t use cedar bark; it repels water and is hard to break down.
- Don’t use cloth barriers or stone.
- Use double or triple shredded leaves or compost.
- Keep mulch fluffed up.
Planting: Plant roses in existing soil. “Like a heretic, I just plant the roses in the soil they’re in because they have to live there. The plant has to survive in the soil it’s planted in. If it can’t survive in the native soil, don’t plant it. You have to make sure the plants you buy can grow in the conditions you have.” Most roses will handle the site you grow in. Roses tolerate a wide range of pH conditions: 4.5-7, but not wet feet. Don’t plant under downspouts or in drainage areas.
Plant at the end of March. Plant knob one inch below ground level and make a hill of soil for roots to spread over. When it starts to leaf out remove the mulch. Put bare root plants in a bucket with a little 7-Up. The CO2 is antibacterial and absorbed by the canes.
Potted roses are really bare root plants in leaf. Carefully cut the pot away (don’t try to pull the plant out) and place the entire soil ball into the hole without disturbing the roots.
Pruning On Hybrid Ts, “cut off as much as you’re happy with from 8-12 inches.” Stagger cuts so canes are of different heights. Form the shrub into a “V” shape by removing all but four or five canes evenly spaced. Take out the center, the oldest and crossing canes and keep the young and healthy. Cut ¼ inch above outward-facing buds. Black spot and downy mildew start in the lower center of the plant on cluttered leaves, then splash onto other leaves, so keep centers open with the “V.” Remove all other branches. Do the same for miniature roses. Roses like to be pruned hard except for Flower Carpet Series and New Dawn
Make decisions before you cut. “The hardest thing is to get people to prune harder. Then black spot and disease come in.” When in doubt, wait until the beginning of April when buds start to push out. If buds expand at the bottom of the bush, prune to that but get the leaves and mulch out now.
Fertilizer: Only feed twice: mid-April and mid-June, then cover with new mulch. If you feed three times, disease and pests come in to attack new soft growth. No feeding after July 15 unless you’re desperate, because it won’t go dormant.
- Choose disease-resistant varieties.
- If a variety is new on the market, wait to see if it does well.
- If we have a cool, wet spring, visit a nursery or public garden to see what’s defoliated. Then, don’t buy it.
- Water infrequently to drive roots deeper into the ground to search for water.
- Frequent watering encourages disease and shallow roots. Roses with shallow roots dry up and die in a drought.
- Prune above an outward-facing bud unless you have to cut the whole plant down.
- Buy plants from reputable nurseries, including online, no box stores.
Prevention is best through proper planting and pruning, watering deeply every two weeks, light fertilization, and good air circulation. “I tend to go to shrub roses because I’m a lazy gardener,” says Van Pelt.
**All images courtesy of Jeff Van Pelt
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published March 26, 2014