POSTED: 1:30 a.m. HST, Feb 7, 2011
Although roses are thought of as plants for temperate climates, they have long been grown in Hawaii. For many years the University of Hawaii's Kula Station in Upcountry Maui has participated as a demonstration garden for the independent plant-testing organization All-American Selections by displaying its yearly rose winners.
Backyard, lanai and community gardeners have also had success in low-elevation areas. At the UH Urban Garden Center in Pearl City, master gardeners have been learning from Honolulu Rose Society members about growing roses at the 19-foot elevation.
The key to growing roses in Hawaii is proper soil preparation. Soil should be prepared to a depth of 18 to 24 inches with a mixture of original soil and equal parts of fine compost (not mulch), manure and bone meal. These materials can be bought premixed at local composting stations, or you can follow application rates on individual packages that can be purchased at your local garden center.
The larger the area you are able to amend, the better. The planting area can be amended by removing the top layer of soil to a spade's depth, then loosening the soil to a second spade's depth. Add the various amendments to fill up to the surface and turn the material into the loosened soil. The planting area should now be a nice mixture of original soil and all the amendments. After planting your rose in the prepared area, a layer of mulch should be applied around the base of stalk to retain moisture and keep the roots cool.
Planting in a container will require you to purchase prepared "container media" at the local garden center. Don't use backyard soil inside containers, as our soils are made up of clay particles that retain water and restrict drainage. Adding backyard soil to a container will restrict drainage and suffocate root systems.
At the Urban Garden Center, we located our new demonstration rose garden close to roadside lights that automatically turn on at night. This is because rose beetles, a common pest in Hawaii, feed at night and can be deterred by light. If you have an area that is close to a household light or streetlight, it is advantageous to choose a planting spot where light can be an option in controlling this beetle pest.
While planning your new rose garden, it is also smart to plant herbs that will attract ladybugs, green lacewings and other predators of garden pests. At the center in Pearl City, we see the most beneficial insects on mature flowering dill, fennel, basil, cilantro and Chinese parsley. Adding these herbs to your planting plan can create a balance in your new garden so that pest control will have the benefit of these six-legged friends.
The Honolulu Rose Society website — www.honolulurosesociety.org/rosecare.html — lists roses recommended by members as reliable varieties for the isles. To receive a link to the many UH publications on roses, e-mail OahuMG@ctahr.hawaii.edu.
The society will offer free classes on "Rose Care in Hawaii" at 9:30 and 11 a.m. Saturday at the Urban Garden Center. Members also will be selling beautiful roses in 3-gallon pots and answering questions from 9 a.m. to noon. Visit www.ctahr.hawaii.edu/ougc or call 453-6055 or 453-6055.
Jayme Grzebik is an urban horticulturist with the University of Hawaii-Manoa Cooperative Extension Service, part of the College of Tropical Agriculture and Human Resources. Reach her at email@example.com.