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  Why Flowers Change Colors

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yardgranny6 blog photos
Joined: 7/05/2007
Posts: 4557
Posted: May/28/2009 6:08 AM PST

Thought this info fitting enough for a sticky, so we can find it more easily. color_104524.htm
Article written by Written by Cindi Pearce -

Colorful flowers exist for pollination purposes--the pollinators, bees and birds, are attracted to certain colors. However, as gardeners we often select flowers based on their hue, not giving much consideration to the real reason why flowers are colorful. Sometimes perennial flowers change colors from one year to the next, which has perplexed many a gardener, who planted red roses and figured he would have red roses for years to come and not some other color. Surprise! Here's why it happens.

There are six main reasons why flowers change colors, according to Sherry Fuller, whose article appears on One of those reasons is due to rootstock. When a plant grafts onto the roots of hardier relatives, this can result in faster growth for the plant. However, if the grafted part dies it leaves the rootstock, which is sturdier, to grow and that can change the color of your grafted flower. It can also affect the plant's abundance and the length of stems, particularly in roses. If you mulch roses well this can ward off this complication to some extent. Fuller recommends watering your plants if it is a dry winter because winter drought can cause roses, particularly those that have grafted onto another plant, not only to change color and lose their original characteristics but to die.

Stress can turn a human's hair gray, so imagine what it can do to a flower. Stress occurs when a plant is moved from one place to another and the result is that the flower can actually change colors, according to Sherry Fuller. For example, if a purple iris is transplanted and in the process is left out of the ground too long, when it blooms in the spring it may be white. Fuller notes that iris growers are perplexed by this occurrence and aren't exactly sure why it happens. Sometimes the flower color will return to its original color, sometimes not.

When a perennial dies out after a few years, it will leave seeds behind. The plants that result from these seedlings are generally more hardy than the plant of origin. However, the color of the flowers produced by the seedlings may be very different from the parent plant, particularly if the parent plant was a hybrid. Fuller notes that the columbine, in particular, is a perennial that routinely peters out after a few years but leaves behind seedlings that produce yellow or white plants.

The color of a flower can be changed due to the alkalinity or acidity of the soil that it is planted in. Hydrangeas will change from pink to blue depending on the soil's composition Acidic soil turns flowers blue whereas alkaline soil will turn the flowers pink.

Age takes its toll on flowers just as it does on everything else and that's why older bulbs are sometimes discarded because an experienced gardener knows that the worn-out bulb isn't going to produce the color of origin. For instance, gladioli may turn yellow and tulips may turn yellow or white as the bulbs age.

When the word "sport" is used in the gardening world, it refers to a flower color or leaf color or plant branch that has changed appreciably. Why this happens remains something of a mystery. It doesn't occur frequently but when it does a new type of flower or plant is created and it may feature unusual colors or form.

Intentionally Altering Colors
Flowers have natural reasons for changing colors but it has been discovered that their color of origin can be altered intentionally, according to Robert Griesbach, a research plant geneticist at ARS Floral and Nursery in Beltsville, Md. The color-producing pigments in flowers include the following: flavonoids, which are commonly found in roses and produce red and blue colors; carotenoids, which produce yellow and orange coloring and are present in marigolds and sunflowers; and chlorophyll, the third pigment, which gives plants their green color. Griesbach explains that through mixing and matching these three pigments, new colors can be created in flowers.

In addition to creating new colors through the mixing and matching of these pigments, Griesbach also discovered that a flower's color can be changed by altering the pH or acidity level of the flower's cell or the soil. If you alter the pH in the cell of a rose the blood red petals could turn out to be pale blue. by Sherry Fuller
SarahJane blog photos
Joined: 3/15/2009
Location: Albany NY
Posts: 1550
Posted: Jun/29/2009 9:11 AM PST

I also wonder about cross pollination, which wasn't mentioned in this article. For instance I had purple coneflowers for several years and decided to buy a "white swan" coneflower. I planted it fairly close to the purple ones. After several years went by, I notice that I have some very pale purple coneflowers too. I thought that at some time they got cross-pollinated. Does anyone else think this is a possibility?
Joined: 5/10/2002
Location: Dayton, OH
Posts: 90
Posted: Sep/11/2009 9:00 AM PST

I have experienced color change with more than one type of plant. My dark purple columbine began turning white several years ago. My son asked me if those were some that Grandma had given me almost 20 years ago. I said they were and he said that old age had caused the change.
5 years ago I planted 3 "My Castle" lupines at the lake house. They actually bloomed that summer, red as they were supposed to. Only one survived the winter and it has bloomed yellow ever since. Disappointing, because I really wanted that splash of red. I've had mums change color, too.
Two years ago I transplanted some irises from here to the lake house. When they finally bloomed this year, the ones in the front were the expected dark purple, the ones around the corner of the house in a newer bed were a gorgeous burgundy. Don't know why except that bed has fresher amendments. Gardening is full of surprises!
Joined: 1/08/2010
Location: Tampa, Florida
Posts: 506
Posted: Mar/10/2010 12:14 PM PST

Thanks for sharing such immense knowledge
Such a neat post
Joined: 5/14/2010
Location: Groton, MA
Posts: 2
Posted: May/14/2010 2:32 PM PST

I have bought columbines in all sorts of colors. The clumps get bigger every year. BUT- the color goes back to it's origin. I now have all pink columbines. Is there anything I can do to change their color?
Joined: 5/14/2010
Location: Groton, MA
Posts: 2
Posted: May/14/2010 2:34 PM PST

How do you change the color?
Joined: 3/16/2010
Posts: 87
Posted: May/17/2010 7:11 AM PST

Thanks YardGranny6 for all your great info. It's amazing what I learn every day on this forum!
ladynla blog photos
Joined: 10/18/2009
Posts: 683
Posted: Jul/01/2011 5:12 PM PST

Have you ever hear of crepe myrtles changing neighbor swears to hers changing...reba
Mont_Albert_Florist photos
Joined: 10/19/2011
Location: Melbourne
Posts: 1
Posted: Oct/20/2011 4:01 AM PST

Very Interesting. I have heard that pandorea pandorana (Ruby Belle) when grown from seed will most likely have an entirely different flower colour to it's parent.
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