Temperamental Dahlias: Climate, Cultivar Performance, and the Tuber Question

Originally published as The Evolution of the Dahlia: Chapter Eleven (1928)

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 Climatic Influence and Temperamental Dahlias, Broomall broadens the inquiry from color and perception to the behavior of entire cultivars under differing conditions. He begins by establishing his authority to compare climates through a compressed account of his residence in several regions of the United States and Mexico, then narrows his attention to Southern California, especially the contrast between inland Eagle Rock and the cooler Pacific coast.

His organizing idea is “temperament.” Some dahlias perform reliably under changing conditions; others bleach, develop green centers, become nearly single, or otherwise fail to produce satisfactory flowers. Broomall illustrates these differences through Millionaire, Elite Glory, Jersey’s Beauty, Ambassador, Amun Ra, Trentonian, and Roman Eagle.

Climate is his most frequent explanation for imperfect flowering, but not his only one. He also names inbreeding, excessive propagation, improper watering, unsuitable fertilizer, disease, insects, and damage to individual branches. His larger argument is therefore diagnostic rather than simply climatic: poor flowers do not necessarily prove poor stock.

That reasoning culminates in his emphatic declaration that “THE TUBER IS NOT TO BLAME,” except where disease or insect infestation actually implicates it. The claim develops a recurring argument found elsewhere in the numbered chapters, but here Broomall places it within a broader synthesis of cultivar temperament, locality, season, and culture.

Published after Broomall had transferred his commercial dahlia business to Charles G. Reed, the chapter appeared as a signed contribution in the 1928 Success Dahlia Gardens Catalog.

The majority of the Growers who read this live East of the Mississippi River, and for that reason I believe it will be an advantage to know what the climate is like where this is written, but first, just to show that I have a fair idea of climatic conditions elsewhere in the United States, I will state that I spent the first 19 years of my existence in S. E. Pennsylvania, after that approximately 2 years in Kansas, 2 in New Mexico, Western Texas and Mexico, 25 in and near Seattle, Wash., 2 in Northern California, Eastern Washington and Idaho, and 20 years in Southern California, and right HERE is the best place in the world to live as far as physical comfort is concerned, and the time is coming when this will be the most densely populated part of North America.

The climate here is not as hot as many Eastern people imagine it to be. It is true that we sometimes see the thermometer register 95 or 100 for two or three days, and between 80 and 90 at midday for two or three weeks, but the heat is seldom oppressive and sunstroke is unknown; the nights are always cool. In 20 years I have not seen a dozen nights that I did not want to sleep under a blanket.

This is not only the best place on earth to live, it is the Hybridists’ Paradise.

In speaking of the effects of climate on Dahlias in Eagle Rock Valley and similar locations from 20 to 60 miles inland, it should be understood that conditions near the Coast where the heat is more tempered by the cool trade-winds from the Pacific are quite different. For this reason some Dahlias that are almost a failure here can be grown much better at the Beach.

For instance, Millionaire never makes a bloom worth looking at with me, but is fine at the Beach. Elite Glory bleaches so badly here that one can hardly tell its true color. Jersey’s Beauty also bleaches by the time it is fully opened unless protected from the hot sun. Ambassador, probably the most temperamental of all Dahlias, will not produce more than five or ten per cent perfect flowers in extreme hot weather, but the same plants in cooler weather will make 80 or 90 per cent good blooms. Amun Ra shows a heavy green center here until late in the season when it becomes cooler, then it will come perfect and is gorgeous. Trentonian threw mostly single flowers early in the season, but later doubled up.

A tuber of Roman Eagle planted early did not make a perfect flower. Green plants of the same variety set out in June produced an abundance of fine blooms for months. My experience causes me to think that, generally speaking, Dahlias that have originated in a hot climate are more apt to succeed under unfavorable conditions than varieties that have originated in a cooler climate.

Here we have a long growing season and to get exhibition flowers I would prefer to set out green plants in June or July. Tubers planted early in the season (February to April) will begin blooming in May or June. Dahlias planted so early are apt to exhaust themselves blooming in mid-summer. If cut back severely early in August, they will make good flowers in the fall, rarely, however, as fine as can be obtained by late planting.

That Dahlias vary greatly in temperament must be common knowledge to every experienced Grower. There are many dependable varieties that rarely fail to come good and give satisfaction; there are others so temperamental that the least interruption of favorable conditions will cause them to fail to make perfect blooms, and indeed there are some kinds so fickle in their actions that they oftimes fail for no reason at all as far as the Grower can discern.

We sometimes see perfect flowers and single flowers on different branches of the same plant; in this case the branches producing the poor flowers are hardened and shrunken by extreme heat so that the flow of sap is restricted, thereby preventing proper development.

While I believe that unfavorable changes of weather are the most frequent cause of failure of plants to make perfect flowers, there may be other contributing causes such as inbreeding, excessive propagation, improper watering, too much water or too little, too often or not often enough, too much fertilizer, or the wrong kind of fertilizer.

In the matter of watering the Grower must learn to use his own judgment; some light, porous soils require an amount of irrigation that would be ruinous in a heavy, compact soil. Plants invariably require much more moisture in hot weather than when it is cool.

I feel that the habit of many Growers in placing all the blame for a Dahlia’s shortcomings on the tuber is a great mistake, and unless the tuber is diseased or infested by insects the practice of throwing away the tubers is the height of foolishness, for in the great majority of cases THE TUBER IS NOT TO BLAME.

The Dahlia, with all its faults and its various enemies, is now and I believe will continue to be THE GREATEST OF ALL GARDEN FLOWERS.

Many varieties of the Dahlia are so sturdy and vigorous that they are a success even when conditions may appear to be most unfavorable. Few other flowers are grown that will do so well, and adapt themselves to such a wide range of climates and elevations, from the Tropics almost to the Arctic Circle.

Fine Dahlias are grown on the Alaskan Coast. Mr. W. T. Pope, of the Hawaii Agricultural Experiment Station at Honolulu writes: “Most wonderful Dahlias are growing at the Volcano Hotel at an elevation of about 4000 feet.”

In fact the success of the Dahlia is world-wide; its lovers are numbered by the million, and as to its improvement we are only just beginning to understand its capabilities.

Dahlia Imperialis—the Tree Dahlia—is now (Nov. 25th, 1927) in full bloom. Once more will I try to cross it with some early blooming variety. I have a great curiosity to see what the Hybrids will be like—IF I get any—Quien Sabe.

J. J. BROOMALL.

1. Broomall’s climatic experience. Broomall compresses approximately seventy years of residence into a single autobiographical statement, naming southeastern Pennsylvania, Kansas, New Mexico, western Texas, Mexico, the Seattle region, Northern California, eastern Washington, Idaho, and Southern California. The figures are preserved as printed but should not be treated as a precise residential chronology without independent documentation.

2. Ambassador and the differing percentages. Chapter Nine gives Broomall’s fuller earlier discussion of Ambassador and reports approximately five percent perfect flowers under one hot-weather condition and nearly seventy-five percent later. Here Chapter Eleven gives five or ten percent in extreme heat and eighty or ninety percent in cooler weather. Both sets of figures are preserved as printed. The surviving texts do not establish whether they represent different observations or approximate recollection.

3. Historical physiological explanations. Broomall explains some failures through heat-hardened and shrunken branches, restricted “sap” flow, climatic origin, midsummer exhaustion, and related causes. These explanations are preserved as part of his historical physiological reasoning rather than as modern conclusions about plant development.

4. W. T. Pope and the Volcano Hotel. Broomall attributes to W. T. Pope of the Hawaii Agricultural Experiment Station a report of dahlias growing at the Volcano Hotel at an elevation of about 4,000 feet. The attribution, quotation, and elevation are preserved as printed but have not been independently confirmed.

5. Dahlia imperialis. Broomall records Dahlia imperialis, the Tree Dahlia, in bloom on November 25, 1927, and says that he will “once more” attempt to cross it with an early-blooming variety. No later source examined for this reconstruction reports the result, so the passage records an intended experiment rather than a demonstrated successful hybridization.