'Earl of Donoughmore' (WL) with very large crimson flowers of fine texture (June), and 'Red Glow' (WL), strong-growing with large, fleshy, crimson flowers in May, both need plenty of room, but 'Spring Dream' (R), with its spreading habit and vivid scarlet flowers (May), is ideal for the smallest of gardens; likewise 'Arkle' (R) with waxy, deep scarlet bells (April-May). Also recommended is the larger 'Lady Chamberlain', red, shading to orange. PINK GROUP Early in the flowering season there are two extremely pretty and valuable hybrids which are not exactly new but as yet they have no worthy substitutes. They are 'Tessa Roza' (WA) with charming lilac-pink flowers in March and very attractive bronze new foliage, and 'Seta' (WA) with very distinctive tubular, bright pink and white-striped flowers also in March. As they flower so early they are best grown where there is some protection from trees which often help to prevent frost damage to blooms. An attractive and free-flowering new hybrid is 'Phalarope' (AR), close in habit with pale lilac-pink flowers (April) and another very useful little plant. 'The Master' (WL), strong growing with exceptionally large pale pink flowers in May, and 'The Queen Mother' (A), more compact with dainty silvery-pink trasses early in May, are both very beautiful plants. Especially good for the smaller garden are two hybrids of R. william-sianutn, 'Moerheim's Pink (A), with large, clear pink bells (early May) and 'April Glow' (syn. 'April Shower') (A), with pretty, frilly, rose-pink flowers in April-May. At the end of the season 'Veldtstar' (WL) makes a spectacular tree with very large, rich pink, well scented flowers, in June-July, and 'Amor' (WA), a somewhat older but little-known plant which should be much more widely grown. Coming towards the end of the season (late June) its rich pink flowers with a dark centre, contrast well with narrow, dark green leaves covered with thick creamy-fawn indumentum. WHITE GROUP 'Caroline de Zoete' (WLA), with purest white flowers of superb shape and texture (April-May) which contrast perfectly with bright, glossy green leaves; these, combined with a good habit, make this an excellent garden shrub. 'Olympic Lady' (A), a pretty R. williamsianum hybrid, is a most pleasing recent introduction from America with pale pink buds opening into dainty white bells in May, and 'Ptarmigan' (R), with tiny leaves and small starry flowers (April), is an ideal plant for the patio gardener. Superb woodland shrubs flowering late in the season are 'Polar Bear' (WL), a handsome tree with light green leaves and massive, scented flowers in late July or August (one of the latest-flowering of all rhododendrons), and 'Northern Star' (WL), also very strong growing with large, scented flowers (July). YELLOW GROUP It is only within very recent years that true yellow-flowered hybrids have been available in sufficient numbers to satisfy the The Wisley Book of Gardening very large demand, and some are still very difficult to obtain.