This section is from "The Horticulturist, And Journal Of Rural Art And Rural Taste", by P. Barry, A. J. Downing, J. Jay Smith, Peter B. Mead, F. W. Woodward, Henry T. Williams. Also available from Amazon: Horticulturist and Journal of Rural Art and Rural Taste.
A few of the most distinct kinds should be treated the same way for the same purpose. The variety called Tricolor is one of the best for that purpose, it being a dwarf grower, and the foliage beautifully variegated.
Oleanders should be planted out for the summer. The true double white and Ma-dorni grandiflora are fine additions to this old-fashioned plant. Never cut the flower stems from these plants; they often flower several times from same stem. Cuttings of these, rooted after the flower stem is formed, make desirable plants to flower a few inches high; we have flowered them in two-inch pots. In this state they are more interesting than the tall, lanky plants usually seen.
Double Chinese Primroses should be removed from the greenhouse to a cold frame behind a north wall, after trimming away all old flower stems and dead leaves. If convenient, these plants give least trouble if planted out in such a frame in the same kind of soil used for growing them in pots. If the plants are at all lanky, which some will probably be at this season, sink them deep in the soil, quite up to the leaves; they will then form fresh roots on the surface, and when taken up, the old stumps may be cut away. These plants are considered rather difficult to keep through the summer. This is partially caused by either pushing the plants into some out-of-the-way corner after flowering, and they are neglected and forgotten, or leaving them standing about on the greenhouse stage until all the life is dried out of them.
Tropaeolum tricolorum should be placed away under the stage or in some other convenient place, and kept quite dry until the autumn. This is one of the best winter flowering creepers for pot culture we have; but, although an old-fashioned plant, it is not so often seen in this country as it should be. In England it is cultivated by nearly every one having a greenhouse.