The Exbury and Knaphill azaleas represent decades of deliberate hybridization, drawing on flame azaleas and other American and Asian species to produce an extraordinary range of flower color. Soft yellows, hot oranges, creamy whites, and deep pinks all appear across the group, often in large trusses that make a spring flowering event of the first order. The deciduous foliage then turns orange and red in autumn, extending seasonal interest well past bloom. Growing 4 to 8 feet tall, these shrubs suit Zones 5 through 9 with unusual versatility.

Moist, well-drained, acidic soil in dappled shade provides the conditions they need. They are more winter hardy than many azalea groups, but they share the family intolerance for waterlogged clay soils. Raise the planting hole slightly, amend generously with organic matter, and avoid overwatering or rich fertilizers that push weak leafy growth. Prune after flowering. Planted in loose groups at woodland edges or in pollinator borders, they naturalize beautifully and reward the patient gardener with decades of reliable spring color.