By Stephen R. Brubaker
The RoseFile

A bit of an understanding of how roses get their color can save a lot of frustration among rose-buyers who care about getting exactly the right color for their landscapes. It will explain why roses having both yellow and reddish tones can be notoriously variable in their coloration. It will also explain why almost all red roses 'blue.'

Roses produce flowers in a spectrum of colors. If one were to take a color wheel and cut from it the two thirds that are green and blue-tinted colors the remaining ones would be the colors of a rose: yellow, primrose, apricot,salmon, copper, orange, vermilion, scarlet, red, crimson, coral, rose, pink, lilac, mauve, purple and white. There are a number of ways to explain how roses produce all their colors and color effects, but the one we will work with here requires the rose to synthesize three colors : blackish magenta (purple), scarlet, and yellow.

Adding scarlet to yellow produces gold, apricot, orange, and vermilion. Adding purple to scarlet produces red, then crimson. And all the colors between any one of these extremes can be produced on a rose petal if the amount of pigment in the petal is reduced. Vermilion fades through coral to candy pink; purple fades through mauve to lilac and pale pink. So a pink flower has the same red pigment as a scarlet one, only less of it. White flowers simply have no pigment.

In this model, gold and orange rose colors result from mixtures of the pigments scarlet and yellow, with gold having more yellow and orange having relatively more scarlet. Red and crimson result from a mixture of scarlet and purple. Primrose is a tint of pure yellow, lilac and mauve are tints of pure purple. In this model, red and crimson and their tints of rose and pink would then result from a mixture of purple and scarlet.

The color wheel to the left shows the colors of roses. The colors ranging from vermilion to pale pink to yellow have very little black in them. Those ranging from scarlet to purple to lilac have some black, making them look cool and sometimes gray or bluish.

This model is a little abstract, but it explains a broad range of behaviors in rose coloration with some very simple models. Take the case of the red rose. A notorious problem of red roses is that they change color when exposed to the sun, they 'blue.' This doesn't mean that they literally turn blue - they actually turn a bit purple - but their appearance looks more blue because a pigment containing yellow has bleached out of the petals making them look blue.

This model is most useful in helping us understand why colors like orange, gold, coral, copper, salmon, apricot, and shell pink are relatively rare in roses compared to colors like yellow, crimson, rose, pink and white. The former colors are more complex. They result from mixtures of two or more pigments. This explains further why the roses with the most complex colorations tend to be most variable. Tiny changes in the amount of one pigment can shift the perceived color quite a bit. If the scarlet pigment in a salmon rose starts to fade, the rose moves quickly toward buff and primrose in coloration. If the yellow fades from a coral or copper-colored rose before the red does, it will change quickly toward pink. A good example is the rose Lillian Austin which fades from coral to pink. Other roses in colors of coral, copper, salmon, and shell pink will frequently display similar traits.

Interestingly, in the saturated colors of gold and orange small pigmentation shifts tend to produce much less noticeable changes in perceived color. Given modest changes in the amount of one of two pigments, gold and orange roses will tend to go on looking pretty much gold and orange. White roses have no pigment,so they don't change color much. Roses in pale pink, candy pink, pink, rose, cerise and crimson tend to be pretty stable and pretty common; most can be produced with one pigment.

This discussion is germane when it comes to choosing roses. Check several sources for a description of color. If they all agree perfectly, you probably know what you are getting. But if they describe the rose differently, it is likely that the rose's color will depend on its growing conditions. In one garden it will be quite different from another. Furthermore, a rose grown in one garden can change quite a bit under varying temperature, moisture, and fertilization conditions. Graham Thomas, for instance, can produce almost buttery yellow blossoms in hot weather, but the color can darken almost to apricot in cool weather in some parts of the country.

And color varies with time. For most blossoms in the apricot color region the bud is relatively dark but the flowers fade markedly as they open. Some China roses darken with age: Old Blush goes from pale pink to a nice saturated pink, and Mutabilis changes from yellow through apricot and pink darkening finally to red. This characteristic was inherited by Masquerade. And in Double Delight the petals start out a pale lemony white. The photo at the top of this page is of Double Delight at the height of the summer. It is only when the blooms are warmed by sunlight that they turn crimson. In late fall, the flowers are mostly pale primrose and just tipped with a blush of crimson. So a single bush might at different times produce flowers so different from each other as to be barely recognizable as being from the same plant.

The process of petals making red or crimson pigment as they age is really not so uncommon in highly bred roses. Nor is the process of yellow fading from the petals. It is little surprise then, that a particular cultivar can come in many different colors. Whether this is a delightful thing to watch in the garden or a bit of a disappointment depends on how well anticipated it is and how flexible one can be in one's color plans. Most good, simple landscaping plans will look more interesting with this sort of thing happening.

This color model also suggests the possibility that if one were to cross a dark purple-toned rose with a yellowish one, the resulting color might include tans,or colors suggestive of brown. And in fact within the last decade roses suggestive of brown coloration have been frequently introduced. There are few, if any, really vigorous ones but that is just a matter of time. Brown and tan tinged flowers can have remarkably interesting colorations, but they can be difficult to place in the landscape. Perhaps they will always be more useful as collector's items.