By Russell T. Nagata University of Hawaii at Manoa College of Tropical Agriculture and Human Resources ADVERTISING Komohana Research and Extension Center The rose is known as the flower of and for love, and is the number one flower type
By Russell T. Nagata
University of Hawaii at Manoa College of Tropical Agriculture and Human Resources
Komohana Research and Extension Center
The rose is known as the flower of and for love, and is the number one flower type that is given on Valentine’s Day. A majority of those roses will be red. In fact, the name rose is derived from the Latin word “rosa,” which means red. While there are many types or groups of roses, a majority of the cut roses are known as hybrid tea, which is characterized by their long and pointed flower buds and many have a sweet fragrance. Other major types are Floribundas, Grandifloras, Polyanthas, Miniatures and Climbers. This year for Valentine’s Day, instead of buying a bouquet of roses, how about buying a living plant that can provide years of enjoyment.
Roses can be propagated from softwood cuttings and the best cuttings are from stems just below a flower (cluster) that completed blooming. Clip off the flower remnants at the first healthy leaf and cut stem piece about 8 inches long using a 45-degree cut. Do not allow the stem to dry out prior to planting. Remove the leaves on the lower half of the stem and apply rooting hormone if you like and set in damp sand/peat medium. Rooting will take several months; during which time do not let the soil medium dry out. Moisture retention can be accomplished with an intermittent mist or a clear plastic bag using several wire hoops to keep the plastic from resting on the cutting. Do not place cuttings in direct sunlight where it could overheat and dry out. Remember to respect Plant Patent laws that protect covered rose varieties. Under Plant Patent protection roses cannot be legally propagated without paying royalty to the patent owner (protection is for 20 years from filing date). Also, at issue is that many of the modern rose varieties do not do well on their own root system due to the lack of disease tolerance and vigor.
The solution to this dilemma is to grow grafted rose plants. Most of the roses purchased today are grafted onto hardy rootstock of either Dr. Huey or Fortuniana which provides more vigor to the modern rose varieties. For Hawaii, Foutuniana root stock work well, since we do not have cold freezing weather and this root stock is nematode resistant.
Rose plants can be purchased as either bare root or in pots. As the name implies bare root plants are shipped without any soil medium. When you purchase a bare root plant, soak the roots in water for about one hour prior to planting. A majority of the roses shipped from propagators are shipped as bare root plants and local nurseries pot these up for your convenience. In addition, potted blooming plants attract many more buyers and can confirm variety identification.
Roses do best where they receive six or more hours of direct sunlight each day. Finding the proper location will provide you with many more blooms and years of enjoyment. When preparing the planting hole, dig to a depth of 18 to 24 inches for maximum root development. Once the hole is dug, fill it with water. As a general rule, if it drains in less than one hour it will be to dry and require frequent watering, and if it takes longer than two hours you may have drainage problems and future root rot issues. In porous soil, add up to 1/2 the volume of the hole with peat or well composted organic material for moisture retention. For poorly drained soil, dig some more until it drains properly, add drainage to the site, find a new location or plant in large pots. Roses require good fertility to maximize plant growth and bloom production. Fertilizers high in phosphorus should be used since it promotes good root and flower development. Many Hawaii soils are deficient in phosphorus and have the ability to tie up soil phosphorus making it unavailable to plants. Conducting a soil testing for available nutrients will take out the guess work out of fertilizing your roses. It is also important to maintain soil pH around 6 for best plant growth.
The most common disease problems with roses are black spot of roses, powdery and downy mildew which are all fungal foliar disease. A whole host of insects also feed on rose plants from beetles, grasshoppers, aphids and mites to name a few. Consult with the Cooperative Extension Service, Master Gardeners or crop care professional for the best control procedures. Always read and follow label directions when applying any pesticides.
For more information on roses and other gardening topics, please visit the CTAHR electronic publication website at http://www.ctahr.hawaii.edu/Site/Info.aspx, or visit any of the local Cooperative Extension Service offices around the Island. I can be reached at russelln@hawaii.edu.
