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.
Plant the crowns two inches deep in rich, moist garden soil, first having shaken off any old soil. When well established and well fed they should produce blossoms abundantly for a quarter of a century. They will also thrive in poorer soils.
Sow the seed in a hotbed or coldframe, and when the seedlings are a few inches high transplant about eighteen inches apart in good soil. Later sowings may be made in the garden. Double varieties produce less viable seed than single ones. The double and some of the choice single ones are often propagated by cuttings.
For earliest plants, sow the seed in a hotbed or coldframe in early spring and transplant the seedlings when a few inches tall about eight inches apart in good garden soil. Sowings may also be made in spring out of doors when the soil has become warm, or in late autumn where the plants are to stand the following season. The first method is usually most satisfactory.
Plant the nursery-grown plants in rich, fairly moist loamy soil. Divide the slowly enlarging clump every five years or perhaps oftener. Give annual dressings of stable manure, and keep clear of weeds, especially grasses, in the clumps. By pinching out the tips of the shoots in late spring the blossoming season may be changed to late summer instead of early summer.
See Ravenna Grass.
Treat like half-hardy primroses. See Primroses. Sow the seed as soon as possible after its collection. A mild greenhouse or hotbed will suit them. The soil should be light, fairly rich and porous, and until the plants are well established should be partially shaded. The hardy kinds do well out-of-doors in partially shaded situations where the soil never becomes dry and where the air is humid. In warm and dry situations they fail. The choice varieties may be propagated by cuttings or division. The half-hardy kinds and those most susceptible to dryness may be bedded out each spring like pansies and removed to deeper shade and greater moisture as soon as they have flowered, their place being taken by other plants. During winter they may be kept in coldframes, previously having been divided.
Start under glass, transplanting the seedlings when about two inches tall to small pots or flats, and when the weather becomes settled to the open ground in a rather sunny sandy place. Allow about two feet between plants. Later sowings may be made in the open ground.
Sow the seeds in early spring where they are to remain, since the plants will not bear transplanting. Choose, when possible, a moderately rich sandy loam, and thin the plants to not less than nine inches for the small growing annuals and eighteen inches for the larger kinds. To lengthen the season of bloom, allow no seed capsules to ripen on the plants. The perennial species may also be propagated by division of the clumps and also by root cuttings taken in autumn and grown under glass. They usually require about twice as much room as the annuals.
Best results are obtained from seed of the present season sown in the early autumn where the plants are to remain, protected during the winter with a light mulch of litter or leaves, thinned to about ten inches apart in spring. They may be thinned to half this distance in the autumn, if they are numerous or crowded. The seeds may also be sown in the open ground in early spring, but they are then rather slow and uncertain compared to fresher seed.
Sow seeds in early spring in a mild hotbed or greenhouse and transplant the seedlings to small, welldrained pots when about two inches tall, and when the ground becomes warm to ordinary garden soil in a moist place. They generally do better if the seed is sown in the open ground where the plants are to remain. They need about a square foot of space each and should be planted in masses.
Sow seeds in a mild hotbed or greenhouse in late winter or early spring. Transplant while small to pots, and when the weather has become settled transfer to the open ground, setting the plants about five feet apart. Will thrive in any soil, but will produce largest specimens in rich. May be grown readily from pieces of root.
Sow seeds in early spring in a mild hotbed or greenhouse and transplant the seedlings while still small to pots or flats, and when the weather becomes settled plant in any good garden soil about a foot apart. Cuttings of the perennial species may be used for further propagation.
When the ground becomes thoroughly warm, sow the seed rather thickly in dry light soil in the sunniest situations, and thin out the surplus to about five inches apart. Usually enough seed will be produced to supply the succeeding season's needs. The plants may be transplanted while in full bloom.
Sow seeds in a mild hotbed or greenhouse in early spring, so as to have flowering plants by winter. Suc-cessional sowings may be made until early summer. Choose light, fibrous potting soil finely sifted. Prick off the seedlings as soon as large enough, first to flats, and when they have three or four leaves to small pots. Give shifts of pots as required. They should be in five or six inch pots by late autumn. They do best at temperatures below fifty degrees and with plenty of food in the form of liquid manure, which should be given only when the pots in which they are to blossom are full of roots. When in blossom they may be taken to the living-rooms. They do better thus managed than if removed earlier. Other "indoor" primroses may be grown similarly.