Flame Azalea

Size, growth and what to expect

Flame azalea is slow to establish, and our growth estimator treats it as slow, about a foot a year. It grows 4 to 12 feet tall and 8 to 10 feet wide.

Trusses of 5 to 10 flowers open in May and June, before or with the new leaves. Each funnel is about 2 inches across, with five long stamens. Eastern tiger swallowtails and great spangled fritillaries carry the pollen on their wings, while bees take pollen or nectar and miss the stigma. The capsules ripen from July to September.

It grows wild in the Appalachians from southern Pennsylvania and southeastern Ohio to northern Georgia and Alabama. Its home is oak woods on south- and west-facing slopes, mountain ravines and the grassy balds, where it makes striking displays.

How to grow Flame Azalea

Flame azalea does best in dappled or high shade with a few hours of sun. It wants a light, acid soil, sandy or loamy, that stays moist and drains well. Afternoon sun scorches the leaves unless the roots stay moist, and it will not stand dense clay. It is a mountain plant and does poorly where summers are hot. Set plants 6 feet apart and keep them 5 feet from a wall. At its size it can go within 15 feet of overhead wires.

Saplings ship potted. Plant dormant plants in early spring or fall, in a hole three times as wide as the root ball and no deeper. Set the top of the ball a touch above grade, and put the native soil back in. On heavy clay, plant on a raised mound or choose another spot. Mulch with pine needles or oak leaves, kept off the stems. The seed is dust-fine and needs light, with no chilling. Sow it in winter on the surface of damp milled sphagnum, uncovered, at room temperature under lights and a clear cover. Seedlings come up in one to three weeks.

Water weekly through the first two summers, since the shallow roots dry out fast, and never dig or hoe over them. Deer damage it often, though it shrugs off rabbit browsing, so cage it where deer are common. Prune, if at all, right after bloom, because next year's flower buds form by late summer.

Each flower carries both male and female parts, yet it sets almost no seed unless butterflies visit, since their wings carry its pollen. Sources disagree on whether a native azalea sets seed with its own pollen, so plant two seedlings from different parents for seed. Lace bugs, aphids and mites can mark the leaves, and root rot takes plants in wet or heavy soil. Every part of the plant is poisonous if eaten, and honey from its flowers can be too.