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.
Resembling their near allies, the Heaths, in their pretty bell-shaped flowers, neat foliage, and dwarf graceful habits of growth, all the species and varieties of this charming genus of tiny evergreen shrubs form appropriate companions, and are usually associated with them in mixed borders, and used largely as edgings to flower-beds, or as front-row plants to clumps of the taller-growing peat or soil plants.
They are all profuse bloomers, and are in perfection in April and May. In common with the Heaths, they prefer a peaty soil, or fibry loam rich in vegetable matter, and should be treated in a similar manner; indeed, few plants are managed more easily, or are less fastidious in their requirements; and they are so thoroughly hardy, that they are never affected by the most severe frosts. All the species are natives of North America, although Caerulea and Polifolia are found wild in some districts in Ireland and Scotland: -
Polifolia stricta. Globularis.