This section is from the book "How To Make A Flower Garden", by Wilhelm Miller. Also available from Amazon: The Well-Tended Perennial Garden: Planting and Pruning Techniques.
Sow the seed in a hotbed in early spring, and when a few inches tall transplant, about twelve inches apart in ordinary soil. A later sowing may be made where the plants are to stand in the garden, the excess being weeded out. Judicious pinching back tends to make the plants more shapely.
For earliest bloom where winters are mild sow seeds in early autumn; for next early, sow in earliest spring, and for succession sow when ground has become warm. When about three inches tall transplant about twelve inches apart in any soil.
Set nursery-grown plants in rich, light loam, provide trellis for the climbing kinds, give annual applications of manure, and mulch with litter during winter. Often the native species may be obtained in the woods. Small plants should be selected in such cases. Do not take them if they are rare in your neighbourhood.
Sow seed in greenhouse or hotbed in early spring; transplant the seedlings as they need it and set in the open ground after the weather has become settled, allowing two feet apart in ordinarily good soil. They may be expected to produce some blossoms the first season, but are more prolific in the following year. Thev are often sown in the open ground, but in this case do not usually blossom until the second season.
Sow the seed in late winter and water sparingly till germination is complete; transplant the seedlings when about two inches tall to small pots and set them in the open after danger of frost has passed. Provide a twenty-foot wire trellis. Greenwood cuttings in sandy soil and gentle heat may be taken from plants growing in the greenhouse.
Sow seed in early spring in a mild hotbed or greenhouse; transplant the seedlings when about two inches tall to small pots or flats, and when danger of frost has passed set in the garden from six to eighteen inches apart according to variety. If the plants ever suffer for want of water, they will drop their leaves. Plant in light, rich, deep, moist soil. For winter bloom sow in late summer.
Take cuttings from garden-grown Slants before danger of frost. When they have struck root, which they do readily, plant in good potting soil in small pots and shift to larger ones as the plants require room. They do best and have the most brilliant colours in bright sunlight and warm rooms or greenhouses. For outdoor planting the cuttings are rooted in midwinter and the plants brought forward to three- or four-inch pots, from which they are set in the open ground about a foot apart for the smaller kinds and eighteen inches for the larger. In a moderately rich sandy loam well-exposed to the sun the plants develop the most brilliant colours. In very rich soil they grow larger, but lack brilliancy.
Plant bulbs three inches deep in late summer or early autumn in light, deep, rich sandy loam and give a mulch of leaves or litter, which should be raked off in spring. The autumn species make their foliage in spring and bloom without leaves in August and September. They should remain undisturbed until the flowers and foliage show signs of failing. Then, after the foliage has died down, they may be dug, divided, and planted in new ground at the proper season.
The spring-blooming kinds may be planted like snowdrops in lawns. Both spring and autumn blooming species do well in rockeries.
Sow seeds in midwinter and transplant when the seedlings are large enough, using small pots or flats.
These plants, if kept growing vigorously, should blossom the first season. Plant in any soil, among rocks, or in borders exposed to the sun, but sheltered from wind. Further propagation is easily effected by division the only safe way to secure plants like the parents if more than one species or variety is growing in the neighbourhood.
Sow •seeds in early spring in a hotbed or mild greenhouse, transplant the seedlings to small pots when about two inches tall, and again to •ordinary garden soil, about one foot apart, when the weather becomes settled. Later sowings may be made in the open ground. If grown as a perennial, the clumps may be •divided in spring when the ground becomes warm. Cuttings may be made for winter use in late summer and for summer use in late winter.
Sow the seed in a hotbed in early spring or in the open ground for later bloom, and, when a few inches tall, transplant about two feet apart in ordinary garden soil. The perennial varieties may be propagated by greenwood cuttings taken in summer and set in a coldframe or by division of the clumps in autumn or spring.
Sow seed where the plants are to remain and thin to about eighteen inches. Any soil will suit. The plants self-sow.
Sow the seed in a mild hotbed or greenhouse in early spring; transplant the seedlings when large enough to handle and as often thereafter as they need, and set in the •open ground when the season has become settled, choosing rather poor soil and fairly sunny situations protected from wind. On rich soil they grow spindling and produce fewer and inferior blossoms later in the season than those on poorer soil. Pinching out the leading shoots of the young plants helps to make them stockier and more prolific.
Sow seeds in a mild greenhouse or hotbed in late winter or early spring. Transplant to small pots and perhaps again before the weather becomes settled, when the plants may be set in the garden about two feet apart mainly to form backgrounds for smaller growing plants.