Chrysanthemum hortorum (Garden Chrysanthemum). Pinch out the tips of shoots whenever they attain a length of 6 inches, until mid-July. When 1-, 2-, or 3-stem plants are desired, they are disbranched as soon as the required number of main shoots has been produced by removing all side shoots when they are large enough to handle. Larger flowers are produced by disbudding, removing all but the strongest buds from each shoot.
Citrus Limonia (Ponderosa Lemon), C. paradisi (Grapefruit), C. sinensis (Sweet Orange), C. taitensis (Otaheite Orange). The only Citruses commonly offered by dealers in house plants are Ponderosa Lemon and Otaheite Orange. The Grapefruit and Sweet Orange usually are started from seeds for house plants. Pruning consists of the removal of weak, twiggy growth.
Coleus (Painted Nettle) can be grown either as a single-stemmed plant or a branching one. Your own preference will decide which. If you plump for the first-named method, it will require taking out axillary shoots, as in the case of Saintpaulia; otherwise just let nature take its course, with occasional help from you in the matter of pinching out shoot tips to prevent blossoming whenever necessary. The flowers of Coleus are not attractive except for a few species such as C. thyrsoideus.
Euphorbia pulcherrima (Poinsettia). The old plants should be cut back to within about 6 inches of the pot in April or May, repotted, and put outdoors for the summer. Cuttings may be taken from the cut-back plants during July and early August. This last method is preferable because it results in plants of moderate size. No further pruning is necessary.
Fuchsia. Resting plants should be brought into light and warmth about the end of January. When the buds start growing, repot the plants and cut back to the strongest shoots. If a bushy plant is required, the tips of the new shoots should be pinched out when they have made six or eight pairs of leaves.
Gardenia. If the plant is getting too large, prune it back one third before you set it outdoors in the spring. When the new shoots are about 6 inches long, pinch off the tips to promote branching. Do not pinch them after July.
Hedera helix. Although English Ivy, Hedera helix, can be used as a house plant, it is better to choose one of the "self-branching" mutations, such as Pittsburgh, Hahn's Self-branching, Manda's Crested, Pittsburgh Variegated, or Shamrock.
Pruning can be done by pinching out the tips of the shoots to make the plants more compact. There is a non-climbing variety, H. h. erecta, which tends toward a sprawling habit. It may require removal of some of the sprawly parts if you wish a compact plant. Rarely, it may be possible to obtain small plants of the arborescent form of English Ivy. The pruning of this requires the removal of the flowering panicles and any shoots which have reverted to the juvenile climbing habit.
Nephthytis Scindapsus aureus (Ivy Arum), S. pictus argyraeus, Philodendron cordatum (Heart-leaf Philodendron), and similar climbing Aroids should be pruned by pinching out the tips of the shoots as soon as they are about 8 inches long. If you have large plants growing on a support, such as a tree-fern trunk, a slab with bark on it, or a stout stick with moss wired on it, wait until they reach the top of the support.
When other trailing plants such as Cissus antarctica (Kangaroo Vine), C. rhombifolia (Grape Ivy), Ipomoea batatas (Sweet Potato), and Boussingaultia baselloides (Madeira Vine) have reached the limits of their supports, the tips of the shoots should be pinched out to stimulate the growth of buds which otherwise would stay dormant.
Pelargonium domesticum (Lady Washington Geranium). Shorten strong shoots in August or September and remove all weak ones. P. hortorum (House, Fish, or Zonal Geranium), when dug up in the fall, should have the top growth cut back at least one half. If they show any tendency to make lanky shoots, pinch off the tips and give them more light.
Rhododendron indicum (Greenhouse Azalea) may be pruned immediately after flowering, but do not cut them back any more than is absolutely necessary to make a shapely bush. During the summer pinch out the tips of shoots which are outstripping their neighbours.
Saintpaulia ionantha (African Violet). The chief pruning to be done on African Violets is that which is necessary to maintain a single-crown plant. It is best accomplished by removing the side shoots when they are barely visible, pushing them out with the aid of a pointed stick or pencil. Other pruning that may be considered desirable is the occasional removal of a wayward leaf.
Tibouchina semidecandra (Princess Tree, Glory Bush, or Spider Flower), a plant of many aliases, which has been called by botanists Pleroma tibouchina, P. macranthum, P. splendens, and also Lasiandra semidecandra, has the good trait of blooming while it is still young. This can be pruned by cutting off the terminal shoots when the flowers have faded.
Hoya carnosa (Wax Plant) needs but little pruning. Merely pinch out the tips of young shoots which are exceeding their bounds. Do not cut off the spurs (stubby growths) from which the flowers are produced.