These magnificent herbaceous plants have long been favorites of the garden and were, I think, once more frequently seen than at present. They do not reward you with their grand flowers if just shoved into the ground as the useful geranium does. They want cultivation and they are well worth it. Excepting as to odor what flower is more perfect than a dahlia?
There are several classes: The show dahlia is the large double flower. The francies are identical except in the markings of the flower. The pompons are perfect little double flowers, not more than one-half or one-third the size of the show flower. The single flowers are very handsome and are used more for bedding. Some twenty years ago they were very much in fashion.
At present the most decorative type is the cactus dahlia and for the commercial florist it is the most desirable. The popularity of the dahlias was on the wane some thirty years ago because of the formal shape of the show type. Then the single varieties came in and quickly became popular as bedding plants as well as decorative flowers. The first cactus dahlia was so called on account of its resemblance to a cereus. There is now as great a variety in this handsome type as there formerly was in the show varieties and they are decidedly the most decorative.
Show and Cactus Dahlias.
With the exception of the single class, or in case you want to raise new varieties of the double ones, the dahlias are easily raised from cuttings. The clumps of roots which have been resting all winter should be placed on a bench in February or March in an inch or so of soil. If there is heat under the bench so much the better. The house can be about 60 degrees. Scatter some light soil among the roots, just sufficient to cover them and keep moist. From the crown of the roots will spring a number of cuttings which when two or three eyes long can be cut off and put into the sand; or you can put each cutting in a 2-inch pot, with a little soil at bottom and sand on top; the latter plan will save disturbing the roots. Always make the cuttings at a joint. This may be of little consequence with the majority of plants but is important with dahlias.
When well rooted in the small pots shift into a 4-inch pot and give plenty of light and air, and as planting time approaches they should be in a cold-frame, where they can be hardened off. The planting time will depend on when you are sure of no more frosts. The aahlia is a cold-blooded plant, yet it can't endure the slightest frost. The first frost of fall kills our dahlias, so a late frost in spring would put you back with the plants for weeks or kill them.
If it is a bed you are going to plant then the whole ground should be deeply dug, and a fourth of its bulk of manure added. The single varieties can be planted two feet apart, the pompons two feet six inches, and the show and fancy kinds to do real well should have four feet. All should have stakes to support them and in a dry time an abundance of water at least twice a week -not a sprinkling, but a soaking. Growers of good dahlias pinch out the earliest flowers and all lateral growths till the plant is three or four feet high.
The single varieties are easily raised from seed sown in February or March. When well up pot into 2-inch pots and shift on, giving all the light and air you can as planting time approaches.
Being assistant to a good Scotch dahlia grower (the late Wm. Vair) in Toronto some thirty years ago, I have not forgotten his method. From plants propagated in March he showed and won a prize the following July 1 for the "best twelve flowers of show dahlias." By the end of May the young plants were fifteen to eighteen inches high in 4-inch pots. For every plant on a long border (five feet between plants) he dug a hole eighteen inches in diameter and fifteen inches deep, working in a third of manure. The surplus soil was spread on the border. Near the center of the hole he drove down a stout stake which was left four feet above the ground and close to that the plant was set. The surface of the soil was left in such shape that when watered the water would run to the plant, not away from it. I think it was about May 20 they were planted. Frequently they were watered and you could almost see them grow. July 1 is extremely early to cut dahlias, but there was a flower or two on several of the plants and after that they were a gorgeous sight. This method could not possibly be followed with growers of acres of these plants and some New Jersey growers cultivate upwards of 100 acres. We have seen them a mass of bloom without stakes or any other care except perhaps water. Although the dahlia is from Mexico it is at its best in the cooler and moister months of September and October.
It is my good fortune to see and frequently to judge the wonderful dahlias shown at Toronto's great fair in September; no better can be seen anywhere and for years the superb flowers of Grainger Bros., Toronto, have been exhibited faultless in shape and color.
It would be useless to give a list of varieties. The catalogues of our leading florists and nurserymen describe them all and the varieties are innumerable. The show varieties have the magnificent self colors of crimson, red, yellow and white and intermediate shades. The fancy flowers are most beautifully blotched, spotted and striped. The pretty little pompons are all colors; some of the pink shades among them are fine for florists' use and the singles are of every color. The cactus type embraces almost all shades ana varies greatly in size and form.
Anything but a very stiff clay will do for soil. The best I ever saw were grown in a sandy loam with a third of good manure added. Deep soil, plenty of manure and abundance of water are the three essentials.
When the tops are destroyed by frost cut down to within six inches of the soil, shake or pick off all soil when lifting the roots and store in a cool, dry cellar or under a bench. Where potatoes will keep so will dahlias - cool as you like but no frost.
If the amateur has no means of propagating, the old root can be planted or divided, leaving an eye or two to each division, and placed in the ground by middle of May; but look out for late frosts if the top has started.
Dwarf Dahlias in Pots.
Dahlias are easily forced and will yield a great quantity of cut flowers during April, May and June. The pompon and cactus types are good for this purpose. Plant the roots two feet apart in six or seven inches of good compost on a low bench or on the floor of a house where you can keep the night temperature 55 degrees. A daily syringing will keep down spider and thrips; fumigation is necessary to destroy aphis. Several strong growths should start from each clump of roots. A stake should be provided to keep the stems from breaking, and when they once show buds keep the lateral growths pinched off. We picked an immense number of blooms off a few dozen plants. Plants that have been grown in 4-inch pots the previous summer and early ripened are better for forcing than those lifted from the ground. In the temperature quoted and if good ripened roots are started, about New Year's you can expect the first flowers in ten to twelve weeks.