This section is from the book "The Gardener V2", 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.
Compared with the many hundreds of species and varieties of this brilliant genus, for which we are indebted to the Cape of Good Hope, and which all require greenhouse culture in this country, the European sorts, well known as hardy Heaths, occupy but an insignificant position. They form, nevertheless, a surpassingly beautiful and interesting group of dwarf free-flowering evergreen shrubs, easily managed, and worthy of far more attention than has hitherto been bestowed upon them. Of the few species from which the now numerous varieties in cultivation have sprung, the mountains and moorlands of our own country have contributed some of the finest, and they are all found in more or less abundance in almost every country in Europe, Growing with the greatest luxuriance in sandy peat, which for the most part forms their natural soil, there is, at the same time, few loams in which they will not succeed, if rich in vegetable matter and free from chalk or lime; while the worst for the purpose may be adapted for all their wants by the application of a moderate quantity of peat or old leaf-soil, and even a liberal allowance of well-rotted manure, which they all appreciate very much.
Several of the showiest sorts - such as the varieties of Herbacea, Mediterranea, and Australis - which flower in the order indicated from February till April, are valuable for winter or spring gardening, and have recently been used with the most admirable results, their neat habit of growth, fresh green foliage, and profusion of bright-coloured flowers giving a gaiety and effect which no other plants could at that season, and contrasting admirably with the early bulbs with which they are associated.
The other sorts - varieties of Tetralix, Cinerea, and Vulgaris - are in perfection from May to September, the one succeeding the other, when Vagans begins to develop itself, and continues till late in autumn.
The smaller-growing sorts make neat edgings to beds or borders, as they may be kept trimmed and neat without disparagement to their flowering. The best way, however, of exhibiting their beauty to its fullest extent is that of grouping them in beds by themselves; and when carefully arranged, according to habit and colour of flowers, nothing can be more attractive. To keep them in health and vigour, it is necessary that they should be lifted every four or five years, and either replaced with young plants, which are easily obtained from layers, or sinking the old plants deep enough to cover the bare stems, which render them so unsightly; this can be done with perfect safety, as the young shoots root freely in a few months immediately below the surface. The operation of transplanting may be performed at any time between September and April, although we prefer spring, as, on the whole, the best for the purpose.
The following list embraces most, if not all, the really fine and distinct sorts in cultivation: -
1st, Sorts with red or purple-coloured flowers.
Cinerea atropurpurea. " coccinea. " rosea. Herbacea.
" carnea. Mediterranea.
Tetralix rubra. Vagans carnea.
". rubra. Vulgaris alpoxtii.
" aurea (golden-leaved).
" flora plena.
2d, Sorts with white or light-coloured flowers.
Cinerea alba. Mediterranea alba. Tetralix alba. Vagans alba.
Vagans alba nana. Vulgaris alba.