This section is from the book "The Gardener V3", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
This is the only British representative of one of the most beautiful natural orders in the vegetable kingdom, Apocynaceae, which comprises many splendid and justly-favoured shrubs and climbers, well known in our stoves and greenhouses. Like most of the other genera of the family, Vinca is more ligneous than herbaceous; indeed, only one species of the group may be properly classed with herbaceous plants, according to scientific rule, but their dwarf habit and natural adaptability to similar purposes bring them nearer to that class of plants than to shrubs of any kind. They are most accommodating in their nature, growing freely in nearly all kinds of soils and situations, preferring moist, shady places, but not refusing to grow freely in those more dry and exposed. They grow freely in the shade and drip of large trees, and may be used for clothing naked banks with great facility and success. Several fine variegated forms also of the hardy sub-shrubby species may be used with great effect for those and for more select purposes, such as the edging of beds and borders of shrubs, draping rockwork and rustic work, and even for the edging of beds and borders of flowers.
All are easily propagated by cuttings, in the autumn or in spring, in a cold frame or under a hand-glass kept moderately close and shaded till the process of rooting has commenced, and by division either in autumn or spring.
Vinca Major is the strongest and largest of the hardy Vincas: it grows from 1 foot to 2 or 3 feet high, according to soil and situation. The leaves are broad, ovate, bright shining green. There are two sorts of branches, those growing erect from the roots and bearing flowers, and those trailing and fiowerless, and rooting as they extend. The flowers are large, somewhat bell-shaped, and blue in darker or brighter shades. It flowers throughout the spring and early summer. It is a native of England, in many parts, and of the south of Europe and the Caucasus. There are several interesting and valuable varieties of this species. A white-flowered sort, not very common, has a fine effect, mixed with the blue, on banks, or wherever masses may be grown. The Vinca major, var. elegantissirna, has the leaves blotched and margined with creamy white, and is an elegant plant for many purposes. Vinca major, var. aurea, is even more beautiful and effective than the preceding. The leaves are richly marked with golden yellow, which in the spring, when young growth is being made, is very beautiful indeed. Vinca major, var. reticulata, is an elegant but not very striking sort, having the veins of the leaves delicately marked with golden yellow.
In rich soils and moist shady situations this is not a constant variety, being apt to run green where over-well fed; but in poorer soil, and more exposed places, the effect of the rich colouring of the veins on the dark shining leaf-ground is very elegant.
Vinca Minor the common Periwinkle, is much more prostrate and slender than the foregoing species, and is, if possible, more useful for covering banks and for planting under trees. The leaves are smaller than those of Vinca major, and they are ovate-lanceolate. The flowers also are smaller, but more profuse: they are also more variously coloured, there being blue, purple, violet, pink, and white coloured varieties. There are also two varieties with prettily variegated leaves, the one creamy and the other golden yellow. It flowers in April and May, and onwards throughout the early summer months. .Native of the same countries as the last, but enjoys rather a wider distribution in northern and central Europe.
This is a very different and distinct plant from either of the preceding. The branches are herbaceous, and have a very limited extension: they are prostrate, and rarely exceed 9 inches in length. The leaves are narrow, oblong, lanceolate; the flowers are blue or purplish blue, and appear in June, July, and August. This handsome and distinct plant is best adapted to the rockwork or mixed border, and prefers a light rich dryish loam in moderate shade. Division and seeds are the most practicable means of propagation. Native of Hungary.