You buy a young potted plant at your local garden center that is not yet in bloom. The tag in the pot pictures a beautiful blue-colored flower. Much to your later dismay, the flowers aren't blue at all, but a purplish lavender. What gives?
hen I first began to consider this color dilemma—with which I’ve been confronted on more occasions than I care to remember—I was amazed at how many factors enter into the altering of a flower’s color. And those factors apply not only to live plants but also to photos of flowering plants we order from hard copy catalogs and from websites.
To illustrate how much plants with the same name can differ in the color of their flowers, let's take a look at the sampling of Google screen shots I've compiled below.
If we take our cue from “Grape Crush,” the name of the impatiens represented above, we might expect a color like the first blossom in the second row. But look how much variability actually exists in blossom color. It ranges from reddish purple (first image in first row) to dark red (second image circled in first row) to dark reddish lavender (second photo circled in second row).
If I had seen only the photo of Daylily ‘Wild Horses’ at the end of the second row, I would have bought it immediately. The contrast of bright white with dark purple is very distinctive and quite stunning.
Actually, that’s exactly what happened. I bought this daylily on the basis of that photo. Only recently did I come across the circled photo in the top row where the flower has no white at all, but rather a disappointing yellow. At that point I googled “Daylily Wild Horses,” and the result is what you see above. I expect my plant to produce its first blossom this year, so I’m anxious to see whether it will actually be the color pictured by the vendor.
I almost bought ‘Shaker’s Prayer’ on the basis of the circled photo in the bottom row. Being somewhat wiser now, I googled it first and found a whole range of shades, including the decidedly lavender blossom of the circled photo in the second row. I decided to pass this one up.
Reputable vendors of this unique salvia called 'Hot Lips' may show you only the first photo in the second row, but they will mention that colors may vary according to weather conditions. As you can see, not all blossoms on the same plant will be bi-colored either. Some will be pure white and others entirely red. Notice that the blossoms in the circled photo in the last row have put on a lipstick with an unexpected pinkish cast.
Tulipa vvdenskyi ‘Tangerine Beauty’ is one of my favorite tulips. It's actually a species tulip that comes back faithfully year after year and even multiplies. Here is what it looks like in my garden. (Click the photos to enlarge them.)
|Tangerine Beauty in one bed
||Tangerine Beauty in another bed
Note the tangerine-colored "flames" on the outer petals of the blossoms at far left. This is what makes this tulip so unique. At left is the same tulip in another part of our gardens. The flames are completely absent. This disparity also occurs in the top row of the screen shot above. In the circled photo in the second row we even find a flower with a pinkish hue.
So, what causes such extensive variability in flower color? Many factors. Here are the ones I've come up with so far.
- Mislabeled plants: A wrong plant label can be attached to a plant while it's in the hands of a grower, perhaps when it's in the seedling stage, when it's maturing in the greenhouse, or when it's dug in the field. The consumer can have a hand in this as well. Say I'm browsing impatiens plants at a local garden center, looking for just the right shade of pink in a sea of flats filled with pink impatiens of various shades. I pull the tags from several to look at cultivar names and growing instructions printed on them. When I'm ready to put the labels back in their packs, I can't remember which tag goes where. I might just stick them back in at random and hope for the best.
- Photos (cameras, photo software): Depending on conditions, a camera may see a flower color differently than the naked eye, resulting in a photo that seems to misrepresent the true color. With the advent of photo software, Photoshop being the most well-known, we can alter the color of a flower to one we find more pleasing. I often wonder how many of the flower images I see in catalogs and online have been photoshopped. I'm guessing that the practice is quite common.
- Innate plant characteristic: In Salvia 'Hotlips' above, we've already seen that plants with the appropriate genetic makeup can change the color of their flowers, sometimes drastically. My most recent disappointment in this regard was the yellow Knockout Rose 'Sunny.' The blossoms very quickly turn to a disappointing off-white. (The mention of genetics reminds me that genetic modification of flower color, whether we like it or not, opens a whole new portal to changing the color of a blossom.)
- Stress: The stress of transplanting, unfavorable weather conditions, or an attack of insects or disease can sometimes change the color of a flower. One of the more unusual color changes sometimes occurs in transplanted irises, especially if they've been out of the ground too long. No matter what color they were originally, they'll bloom white! The next year they may change their color again, but not necessarily to the original one.
- Age: A color change often occurs in a flower when it ages. We've already noted the fading of the yellow color in the Knockout rose 'Sunny." But the change doesn't always involve fading. For the last 10 years or so I've been growing a potted Brugmansia. It blooms white but the blossoms age to a pretty shade of pink.
- Soil: Soil pH is a determinant in the color of certain hydrangeas, but generally does not affect flower color in other plants.
- Light: Low light may result in lighter flower color in some plants, but bright light may have the same effect. Sometimes the actual color of a flower may not change, but we see it as a different color. When we see flowers in the warm or reddish light of morning or late evening, we will see a slightly different color than if we see it midday. The blue background of an open sky or the green light under trees will cause us to see the color of the same flower as differing slightly. The color we see is actually the color of light reflected off the flower, so whenever there is a change in this reflected light, it will change our perception of the color.
- Temperature: Many orchids--and other blooming plants as well--will have a darker flower color in cooler temperatures. This is especially true of flowers that are in the yellow to red range. Temperature affects the production of the chemicals (anthocyanins and carotenoids) that produce these colors. At higher temperatures lesser amounts of these substances are produced, so the flowers are paler in color. At lower temperatures the opposite is true.
Salvia 'Hot Lips' discussed above responds in a different way. Cool temperatures will produce more bi-colored blossoms. The Brugmansia I mentioned also responds to very cool temperature by producing white blossoms that don't age to pink.
- Sports: While highly unlikely, it is possible that the plant you purchased is a "sport." Sports develop when genetics goes awry, and an offspring or a portion of the parent plant develops an unexpected change in traits. One of those changes may involve flower color. Others include changes in flower shape, number of petals, and variegation.
- Rootstocks: If you grow grafted plants (where one plant variety is grafted onto the rootstock of another), you may see a color change in the flower and even in the habit of the plant, if the top dies and the rootstock sends up new growth. Many of us who grow roses have experienced this phenomenon when the rootstock survives the winter, but the top part of the graft doesn't.
- Seedlings: If you grow plants that self sow, you may have discovered that the flower color may no longer be the same as that of the parent. This is especially true if the parent is a hybrid. Hybridized varieties have progeny that reflect the plant's genetic history.
- Gender: Yes, flower color perception may even be gender dependent. The flowers don't actually change color, but men tend to see only primary colors such as blue or green, whereas women make finer distinctions such as turquoise or lime.
Such perception has a physical basis. The genetics of eye anatomy really do differ between males and females, and the difference affects how we males see color. My wife may say: "Look at that beautiful maroon daylily over there!" My response will most likely be: "Where? Oh you mean that purple one over there." It is possible, however, to teach us color challenged males to make finer distinctions. I've been working at it and am happy to report that I'm making progress.
I've compiled a chart below, based on scientific observation, that illustrates the difference in perceptions between the sexes. The color names are actual registered colors.
So there you have it. A full dozen ways that affect flower color or how we perceive that color. Can you think of others? If so, I'd love to hear from you.