16 Jan 2006

                                               By Joel Ross M.D., ARS Consulting Rosarian

     While the bloom should not be your only consideration in choosing a rose bush, the fact of the matter is that this turns out to be the PRIME consideration. There are three major factors that attract us to blooms, their color, fragrance and shape.
It is important to see live blooms grown by someone experienced in rose horticulture at various times of the year to appreciate their true colors. As I visited Geri McCarron's gardens, she explained to me that even with optimal feeding, watering and pest control, bloom color varied by amount of sun exposure, the physical place to which the plant is assigned in the garden (e.g. southern versus eastern garden sector) and ambient temperature. Because we all live in different microclimates, we should expect the blooms to look just a tiny bit different from one garden to the next. Geri actually has two different gardens, one within a mile of the beach and another within a hot inland valley. Blooms of the same cultivars from these two locations can appear quite different even though grown by the same experienced Rosarian. Also bear in mind that some blooms naturally have different colors at different times of the year. Sunset Celebration (pink/orange) and Leonidas (brown-red/orange) are such examples. Plant picture ID tags can be a major source of confusion regarding color. Many of us (myself included) have been quite shocked when our blooms did not appear true to color when compared to the “gorgeous picture” on the plant ID tag. Assuming the plant was not mislabeled, one needs to realize that as ink colors are combined and printed, the hue, chroma and brightness may vary from the real item. One only needs to compare tags on the same variety from several different hybridizers to realize that the buyer should not rely on these colors. As John Bagnasco has pointed out, it is also important to see how long the true color of a rose lasts. For example, all dark yellows are not created equally, some fade faster than others. Many roses hybridizers capitalize on this trait by inventing snappy sounding names e.g. Abracadabra or Joseph's Coat. Think whether the name suggests fading and whether you can tolerate this. Be especially wary when the hybridizer tells you that the colors are  “constantly changing and thus hard to adequately describe”. The actual translation is “ this rose fades so quickly that no one is even sure what the real color is”. The same admonition holds true for those blooms described as ” starting out as deep red and finishing off as a lovely light pink”.  Maybe this makes for great color and maybe not.  Much depends upon the eye of the beholder.
     Fragrance is probably the key bloom characteristic for most people, assuming even more importance than color. I say this based upon a long experience of watching the general public as they meander among rose specimens at our shows. Almost to a person they bend over placing their nose squarely in the middle of the bloom and inhale deeply. This proves to be a disappointing experience for most as only about 15% of all blooms are fragrant. The ability to perceive fragrance varies with the observer as does hearing and visual acuity. Some fragrances are not sensed as strongly by some observers or at all by others. One may have an inability to smell one fragrance but no impairment in sensing another. Some blooms have fragrances that some people find objectionable or even allergenic. Collectively, roses display several dozen different fragrances. Fragrance is easiest to detect in the early afternoon in warm but not hot environments.  Fragrance does fade as the bloom ages.
     Shape of the bloom and the expected number of blooms per stem are important characteristics that most people fail to consider sufficiently prior to purchasing rose plants.  They need to give some thought to numbers of blooms per stem: single, single with accessory buds or multiple.  Single blooms lend themselves to long stemmed specimens fit for exhibition or display. While accessory buds tend to decrease the size of the center bloom, if the specimen has ”good vase life” those side blooms are an advantage as they can significantly extend the specimens display time.  On the other hand, accessory buds that are seen as annoying appendages that need be constantly removed (disbudded) to allow for proper center bloom growth are a distinct disadvantage. Sprays need to be appreciated for their multiple but definitely smaller blooms that create an “eye catching” garden display. Thoughts of sufficiently disbudding sprays to make them look like single blooms for table display purposes need to be abandoned before one purchases the plant. The plant tag is CRITICALLY IMPORTANT in showing bloom form. The pictures on these tags are not chosen haphazardly. They depict the bloom in its most nearly perfect form. If there is something about the bloom form that you find unappealing on the tag picture, then DO NOT purchase the plant. You will NOT be able to do a better job growing it than “the guy” whose plant was photographed. Do try to decide what makes the bloom unappealing to you. Put it into words so that you can quickly identify these traits each time you view plant photographs. This deadly critical appraisal is important if you really want to avoid buying unsuitable plants. Petal count is important in most cultivars. As a general rule, the larger the petal count, the more heat required to open the bloom. Speed of bloom opening is critical to vase life. My neighbor, Jerry Weiner, has coined the self -explanatory term “blow heads” for blooms that open too rapidly. There are cultivars that regularly appear as buds in the morning and become fully opened blooms by mid-afternoon.  I find no satisfaction at all in growing these cultivars. I have all but eliminated them from my garden no matter what their other redeeming characteristics. Bloom appearance needs careful consideration. If you desire those nice spiraling high centered blooms, you need to pick blooms whose individual petals are TALLER than they are W-I-D-E. The reverse measurements are INCAPABLE of producing a tightly spiraled center. Frank Grasso advised buyers to disassemble a bloom petal by petal in order to examine the petal form and structure (body) prior to purchasing a plant. While it might sound extreme or odd, I observed hybridizers and very experienced Rosarians doing just that in the Wasco flower fields as they determined which plants would be further developed or discarded.  On the other hand, this is probably a really bad idea in a retail Nursery where plants for sale may only possess a bloom or two. As a general rule, the proprietors do not appreciate this sort of activity. The bloom's ability to withstand high humidity or just plain rain or irrigation water may also be important. Some blooms literally disintegrate if exposed to water. Others contract botrytis, a fungal disease that begins as pink spots on the petals but soon degenerates to brown blotches of a mushy consistency with wasting of the bloom. Worse yet, the infection is capable of spreading to neighboring blooms and plants. Unless you are prepared to spray to remedy this problem, you will want to give it some consideration in advance to the bloom's susceptibility to botrytis.
     Since blooms are not the whole story when purchasing plants, we will discuss other important characteristics in future articles.

Dr. Joel Ross

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