Color in Dahlias: Climate, Soil, Variegation, and the Search for Blue

Originally published as The Evolution of the Dahlia: Chapter Seven (1924)

Original text by J. J. Broomall is in the public domain.

Compilation, editorial notes, introduction, biography, and revised text copyright © 2026 by Steve K. Lloyd. All rights reserved.

In Color in Dahlias, Broomall takes up the subject he had expressly postponed in Chapter Six. Having distinguished temporary loss of doubleness from changes in color, he now makes color variation itself the problem. Flowers of the same named variety, he observes, may differ enough under different conditions that even experienced growers can have difficulty recognizing them.

Broomall attributes much of this variation to climate and to the chemical properties of soil or plant food. Golden West, Helen Durnbaugh, George Walters, and Countess of Lonsdale provide examples of color changing with heat, sunshine, shade, and cool weather. From these observations he moves into more speculative territory, including the possibility that understanding soil chemistry might someday help produce a genuinely blue dahlia.

The chapter becomes especially important when Broomall turns to variegation and apparent reversion. His account of Mrs. Alfred Paine describes a white variety progressively producing old-gold flowers until, by his account, the white form disappeared entirely. Yet he closes with a significant qualification: even an observant grower may reason incorrectly from effect to cause. That admission gives the chapter a more exploratory character than some of his more categorical discussions of variation.

The chapter takes up the color subject postponed in Chapter Six, although Chapter Seven itself does not explicitly look backward to that postponement.

The text printed here is from J. J. Broomall’s 1924 Dahlia Guide.

Few plants in cultivation show a greater variation in color than the Dahlia; not only is there a great range of color and tints in the innumerable varieties that have been produced, but it frequently happens that flowers of the same variety differ so much that even an expert will fail to recognize the variety.

While there may be many causes for this variation which even the most observant grower has as yet been unable to account for, I believe the chemical properties of the soil, or rather, of the plant food in the soil, and changed climatic conditions are the two most frequent causes of these variations.

First, it is an established fact that some Dahlias will fail to show their correct color in extreme hot weather, while there are others that seem to glory in hot sunshine, and will not assume their correct color without it.

I know of no two Dahlias that will better demonstrate the influence of heat than Golden West and Helen Durnbaugh.

Golden West likes a moderate amount of warm sunshine, but if it is extremely warm, the flowers will be pale and lack the rich orange shading that is the glory of that variety; it is this rich, lustrous orange tint that causes it to show so well under artificial light and which is chiefly responsible for its long continued popularity as a commercial cut-flower.

While speaking of the Golden West I wish to call your attention to the fact that I introduced it in 1913, and in 1923, eleven years after its introduction, it won first prize in the Los Angeles Show for the best 25 cut blooms in the show, surely a record unequaled by any other Dahlia.

I will further call your attention to the fact that light yellow flowers will not show to good advantage under artificial light, as light yellow will often be mistaken for white, unless they are close alongside of pure white, and even then they are not very attractive.

Helen Durnbaugh not only succeeds well in hot sunshine but must have it to be seen at its best; in a shady position, or in cool, cloudy weather it will be a failure as far as color is concerned; it requires warm sunshine to develop that glowing pink tint that makes it so attractive.

Such salmon-tinted varieties as George Walters and the old Countess of Lonsdale will vary so greatly with changes of temperature as to be scarcely recognizable.

I have seen Countess of Lonsdale when it was almost red, and again, under different climatic conditions, when it was a pale fawn or amber, with not a trace of salmon-red in evidence.

I cite these few as examples, but there are many others just as greatly affected by different temperatures.

In my opinion, the chemical properties in the soil are the greatest determining factor of the color of the Dahlia when it is originated, as well as the most frequent cause of its variation in color in different localities in which they may later be grown.

If we could find out by experimenting what fertilizer or plant food showed a tendency to increase or improve a certain desired color, then we should be able to find out by chemical analysis the element in that plant food that causes the desired effect, and if this can be ascertained I can see no reason why we cannot obtain flowers almost any color we may desire.

As to whether we will ever be able to obtain a real Blue Dahlia I will not venture to predict; twice since I have been raising Dahlias “Blue Dahlias” have been offered to the public; I invested in one of these, to my sorrow; it is possible that I may invest in another, after I have seen it.

A Blue Dahlia that is a real, true Blue is yet to be produced, but I do not regard a Blue Dahlia as an impossibility.

We have a number of Lavender and Purple Dahlias that show blue rays under certain conditions, but all are a long ways from being pure blue.

If we can find out what chemical property in the soil, or in the plant food, it is that causes these blue rays then we should be able to increase them.

I have never been very partial to Variegated Dahlias chiefly for the reason that there are very few of them that will STAY VARIEGATED; there is always a tendency in most Variegated Dahlias to run to solid color and generally to the darker color in the flower.

The cause of this seems to me to be that the darker color is apt to be nearest to the original color of the Dahlia before it was brought under cultivation, while the lighter colors may be considered acquired colors which have been produced by change of environment and plant food.

And so we find in most Variegated Dahlias a tendency to revert to the original color of the Dahlia, or to the color nearest to the original color, which means, of course, a corresponding loss of the acquired color.

One of the most complete changes in the color of a Dahlia that has ever come to my notice occurred in one that I raised in 1902.

As the seed from which it was grown was not of my own growing but was obtained from Henry Cannell of England, I know nothing of its parentage.

This Dahlia, which I named Mrs. Alfred Paine, was a glistening snow white and it was the finest White Cactus Dahlia I had seen at that time, and for some years after.

The outer petals sometimes showed a faint edging of bronze-yellow or old gold, but in most of the blooms it was scarcely noticeable.

In 1904 this produced a plant on which were flowers old gold in color without a sign of white in them; the plants that remained white at that time continued to make more of the dark colored flowers year after year until in 1909, after I had moved to Southern California, the flowers ALL came the darker color, and as a White Dahlia I had lost it entirely.

There is another case of variance in color in my gardens; I do not know if it is so with other growers to the same extent or not, and that is that most of the Dark Maroon Dahlias I have grown seem inclined to become purple.

While I do not feel certain as to the cause of this, I think that my soil is deficient in iron and am inclined to think that this may have something to do with the failure in color.

Here is a chance for investigation and I would be pleased to hear from other growers in regard to this or any other points I have mentioned.

While it is not possible for even the most observant grower to always reason correctly from effect to cause, there is certainly a great opportunity for us to obtain a better understanding of the Dahlia, and a better understanding will undoubtedly result in BETTER DAHLIAS.

J. J. BROOMALL.

1. Golden West chronology. Broomall states that he introduced Golden West in 1913 and that its 1923 Los Angeles prize came “eleven years after its introduction.” Both readings are preserved as printed, although the interval is inconsistent with ordinary elapsed-year calculation.

2. Soil chemistry and flower color. Broomall proposes that particular soil constituents or fertilizers may determine or intensify dahlia colors and might eventually make otherwise unattainable colors possible. This is preserved as his historical hypothesis rather than as a statement of modern genetics, pigment chemistry, or plant nutrition.

3. The blue dahlia. Broomall regarded a genuinely blue dahlia as possible, although he acknowledged that the lavender and purple varieties then available were far from true blue. His discussion reflects the state of his own speculation in 1924 and should not be read as a modern account of the biological limits on blue coloration in dahlias.

4. Variegation and reversion. Broomall interprets darker colors as nearer the dahlia’s original state and lighter colors as acquired through environment and plant food, leading variegated forms to “revert” toward darker colors. This is his historical causal theory. His later writings became less categorical about the causes and permanence of clonal color changes.

5. Iron deficiency. Broomall suggests that a deficiency of iron in his soil may explain why dark maroon dahlias tended toward purple, but he explicitly presents the idea as uncertain. That uncertainty is preserved as part of the historical record.