How to grow roses
A rosarian of 50 years wants gardeners to know that despite what they may have heard, these lovely plants are not difficult to grow.
Tue, May 22 2012 at 2:45 PM
ROSES AREN'T ALWAYS RED: The rose shown here is Iceberg. It is considered one of the world's best-known roses. (Photo: Tom Oder)
Jeffrey Ware is working hard to shatter a myth.
The myth, he says, is that roses are difficult to grow.
To help prove his point, for the last four years Ware, executive director of the American Rose Society in Shreveport, La., has been working with Louisiana State University on a project to identify roses that are resistant to blackspot, a disease that bedevils rose growers in most regions of the country.
The trial, the Easy Tea Hybrid Tea Rose Research Project, involves 30 hybrid tea roses. Research will end in October and winners will be decided in November, according to Allen Owings, professor of Horticulture - Nursery Crops and Commercial Landscaping at the LSU AgCenter in Hammond, La. Owings expects three to five plants will be identified that can be grown in home gardens with what Ware describes as minimal chemical intervention.
Hybrid tea roses are the classic, long-stemmed, florist type of rose most people usually think of when they think of roses, said Ware. Easy Tea is the designation that will be given to “winning” roses that pass the trial.
When those winners will be announced to the public is still being discussed, but Ware said easy-to-grow roses are available at garden centers nationwide even now. Emphasizing that he’s not just talking about the popular Knockout Roses, he cited two Floribunda roses, “Walking on Sunshine,” which has yellow flowers, and “Easy Does It,” which has apricot-colored flowers.
If you’ve been drawn to the allure of the flower that Congress voted the National Floral Emblem in 1986 – which Ware, admitting bias, compares to the bald eagle being the national bird — but you’ve been frustrated because your plants didn’t grow well, here is a cultural guide to change your opinion. These growing tips were offered by Donna Burt, of Dunwoody, Ga., a rosarian and member of the American Rose Society who has been growing roses for 50 years.
Choosing a site
Roses need 6-8 hours of sunlight to bloom well. Roses grown in northern states need more hours of sunlight than those grown in the South. This is because the further one is from the equator, the lower the angle of the sun and its intensity.
Digging a plant hole
The saying “dig a $50 hole for a $5 plant” is especially true of roses. The roots want to spread out. Digging a small hole, especially in heavy soils, will cause the roots to wrap round and round like they were still in a pot. How big should the hole be? Make it three or even four times as big as the container.
Amending the soil
When digging the hole, place the dirt in a wheelbarrow. Because the roots need soft soil in which to spread out, amend the dirt from the ground with organic material. Additives can include compost, peat moss or organic soil additives from garden centers. Amend the dirt at the rate of one-third to one-half additives to the amount of dirt in the wheelbarrow. In heavy soils, add sand to increase drainage.
An amended mixture is also important in sandy soils because these additions will help sandy soils hold water and nutrients, which otherwise might drain below the root zone. Think of what would happen if you dug a hole in the sand at the beach and poured water into it, Burt said.
Organic fertilizers such as cotton seed meal and blood meal should be added to the amended soil. Be sure to apply at the rate suggested on the package. Mix all ingredients in the wheelbarrow.
Planting the rose
Planting techniques will vary slightly from warm to cold climates. The difference involves the graft, which Burt describes as the lumpy place on the stem where the growing portion of the plant has been grafted onto root stock. Most commercial roses, she points out, have been grafted because this allows growers to get plants to market quickly.
In warm climates, when the soil is backfilled around the plant, the graft should be about an inch above the planting bed. In cold climates, it should be an inch or more under the ground. In some areas, such as Minnesota, Burt says the graft is planted three inches below the soil surface.
If the rose is growing on its own root stock, plant it at the same level as it was in the pot. Miniature roses, she said, are typically grown on their own root stock and are not grafted.
If in doubt about the location of the graft, ask at the nursery where you buy the plant.
Potted roses are usually not root-bound, but if the one you have is, loosen the roots as you would for any other plant before planting it.
For plants that have arrived by mail order and are bare root, soak the roots, or even the whole bush, in plain water for 5-6 hours before planting it. This will help rejuvenate the plant if it dried out during shipment.
When backfilling the planting hole with the amended soil, trickle water into the hole when it is half to three-quarters filled. This will settle the soil down. The goal is to keep the plant from sinking once it has been planted and watered.
Heel in the plant when the hole is completely backfilled and water thoroughly. To keep the plant from drying out, water every two-three days for the first few weeks. Don’t assume you don’t have to water because there was a pop-up shower. Brief rainfalls often don’t provide sufficient water to plants, especially those in shock from just being planted. To measure and monitor rainfall, purchase a rain gauge from a garden center. Burt considers a rain gauge an essential garden tool.
Roses are heavy feeders. They can’t read, though, and don’t have to have a fertilizer developed just for roses, Burt advises. The same fertilizer that is used on lawns or ornamentals can be used on roses as long as it is not too heavy in nitrogen, Burt said. Nitrogen is the first in the three N-P-K (Nitrogen, Phosphorous, Potash) numbers on fertilizer packages. Burt prefers a slow release 14-7-7 fertilizer. The higher concentration of nitrogen causes new growth, which is important because roses bloom on new growth. Follow package directions for rates and frequency of applications.
The goal is not to treat disease but to prevent it. The disease most often associated with roses is a fungus called blackspot. The bane of many a would-be rose grower, the signs of blackspot are yellowing and spotting of leaves that drop from the plant. To prevent disease, Burt begins a weekly fungicide spraying regimen as soon as she plants a new rose. Fungicides are readily available at garden centers.
Because there are so many beneficial insects, Burt prefers not to spray for insects. She would rather use a strong stream of water from the hose to knock off sucking insects such as aphids. If there is an infestation of Japanese beetles, Burt suggests paying the neighborhood children a bounty of a penny or more for each one they collect and put in a jar — an idea that she admits is not original. Commercial insect sprays are available at garden centers if the bugs become too much.
The mantra on pruning, Burt says, is to force out new growth and leave the center of the plant open. The theory is to create air movement in the center of the bush, which will reduce the chance of disease. But Burt says this can result in an unattractive bush. She says the plants are better served by pruning to create an aesthetic, pleasing look. She accomplishes this by cutting out crossing branches and avoiding twiggy growth.
To prune, look for a bump of tissue along the stem. This is a bud that will create a new shoot. Cut the stem about a quarter of an inch above the tissue to force the new growth. Cut at an angle so water will run off and not collect on the cut, which could lead to rot.
Pruning forces new growth, and it is the new growth that produces blooms. Deer love tender new leaves, so gardeners who have a deer problem will need to protect their plants from them.
If gardeners will follow these few guidelines, Burt believes they will help prove Ware’s theory that roses really aren’t that hard to grow.
They may become even easier to grow when the new hybrid teas from the LSU test arrive in garden centers.
Inset photo of Easy Does It rose: Gene Sasse (c) 2008 courtesy of Weeks Roses
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