Chrysanthemum. When you have bought or raised single-stemmed, rooted cuttings and want them to develop as bushes, the tips should be pinched out with thumbnail and forefinger to stimulate buds into growth below the pinch. The resulting branches, in turn, should have their tips pinched out when they have grown to a length of about 6 inches. Continue doing so until July. Pinching is unnecessary when you are growing so-called "Cushion Mums" and "Azaleamums," which are naturally bushy and do not need any encouragement to branch.
On the other hand, you may want to grow the large-flowered kinds which have come to be associated with the football season and Thanksgiving. These, contrary to the Garden Chrysanthemums, need to be disbranched and restricted to one, two, or three shoots per plant. But you must have the right variety. There is no point, for example, in growing small-flowered Button Chrysanthemums to a single stem and allowing only one flower to develop. Among the right varieties are: Chrysolora, Early Frost, Good News, Golden Wave, Indianola, Mrs. H. E. Kidder, Rose Perfection, Silver Sheen, Smith's Superlative, and Stately White.
Most of them are comparatively late bloomers and may be caught by frost. Usually these are grown in pots so they can be brought under cover if frost threatens. Each shoot should have a separate stake to which it is tied. Any shoots which appear in the axils of the leaves should be removed as soon as they are large enough to pinch out.
The selection of the kind of flower bud is important. The first one to appear is called the "first crown bud." With most varieties this does not usually give a good bloom, so it is removed. Then the second crown bud appears, which may be the one. If, however, this one is passed up, you have another chance in the terminal bud.
The time for "taking" (choosing) these buds has been worked out by florists so that the beginner does not have to worry so much about which bud will be the best for him to keep. It is told in the catalogues of the dealers who specialize in Chrysanthemums.
Dahlia variabilis (Dahlia). The stock for planting may consist of a fleshy tuberous root which is cut from the clump (which grew the preceding year, was dug up in the fall, and kept in a cool, dry cellar over the winter) to include an eye (growth bud), or may be "green plants" obtained by rooting cuttings.
When the shoot has grown to the height of 12 to 18 inches, the tip is pinched out with a thumbnail and finger. Usually the pinch is enough to obtain a sufficiency of strong branches, but if only two to four are obtained, further pinching may be necessary to obtain the required number, which will be six or more.
The treatment from now on will be concerned with disbudding, which consists of removing all flower buds except one to each branch. Usually the one that is left will be the terminal bud. Treated in this way, the energy of the plant will be concentrated in the few buds that are left, and admirable flowers with long stalks suitable for exhibition will be produced.
If you are concerned mainly with flowers for home consumption or for garden display, you can forget about pinching and disbudding except for the removal of faded flowers. The small-flowered kinds — Miniatures, Pompons, and Balls — need no disbudding.
Delphinium. When the flowers of Delphinium have faded, cut them off to prevent them from going on to produce seed. Then, a few days or a few weeks later, when the leaves look ratty, cut all stalks down to the ground. Treated in this way, there is a possibility of getting another crop of flowers before frost.
Dianthus plumarius (Cottage Pink) and similar low-growing carpeting plants should be sheared either with grass or hedge shears to remove the flower stalks as soon as the flowers are faded. Others in this group are: Viola cornuta (Tufted Pansy); Veronica, dwarf and dwarfish varieties such as V. teucrium, V. spicata, and V. incana; Lobularia (Alyssum) maritima and Alyssum saxatile (Golden Tuft); Armeria maritima (Thrift); Iberis sempervirens (Perennial Candytuft); and others.
Iris. Tall-bearded Irises are pruned when they are transplanted by cutting the leaves back one half to two thirds. This can be done with ordinary scissors or one-hand grass shears. The only other pruning that may be necessary at times is to cut out, with a knife, portions of the rhizomes when they have been attacked by iris borers.
Phlox carolina (Summer-flowering Phlox), the early-blooming kind, and P. paniculata (Summer Perennial Phlox), of which there are innumerable named varieties, should be pruned early in the spring when the shoots are about 2 inches high by removing all but three of the strongest shoots. This is assuming that the individual plants are spaced about 1 foot apart. It is essential to cut off the panicles of faded blooms to prevent self-seeding. The seedlings, which revert to the ancestral forms, are more vigorous than the named varieties and consequently crowd out the original planting.