🌺 Mrs. G. G. Gerbing Rhododendron
What it looks like
Why this variety
Mrs. G. G. Gerbing — ‘Gerbing’ in the trade — is the white Southern Indica azalea: huge, single, pure-white flowers, opening in spring on a vigorous evergreen shrub 6–8 feet tall and wide. White flowers in a shade garden do something no other colour does: they glow at dusk, when the garden is winding down and the gardener is actually outside to see it. Gerbing is the azalea for a moon garden, a shady entrance, or a pairing with pink Indicas that need a white neighbour to set them off.
In Florida, Gerbing is at home in the north and central peninsula in part shade, acid soil and steady moisture. It is a touch smaller and tidier than Formosa and Taber, which makes it the white Indica for a foundation bed that cannot hold a 10-foot shrub — though 6–8 feet is still a real shrub, not a filler, so give it room and do not shear it into a box.
How to grow
Florida honesty, in the good direction for once: these are not the northern rhododendrons that melt in Florida heat. Southern Indica azaleas are evergreen azaleas — and azaleas are rhododendrons, botanically speaking — bred for the Gulf South, with big, showy spring flowers in white, pink, red and purple on shrubs 6–10 feet tall. Plant in fall or spring in part shade — morning sun, afternoon shade — in rich, moist, well-drained, acidic soil amended with pine bark and compost, and mulch thickly with pine bark or pine needles. Water faithfully through the first two years; Indica azaleas are thirsty shrubs and a dry spring costs you the bloom. Keep them away from concrete and limestone, which leach alkalinity, and site them where a 6-foot shrub will be welcome in five years, not where it will be sheared into a box.
Water & feeding
Water deeply and consistently; Indica azaleas hate drying out and bloom best with steady moisture. Mulch 3–4 inches deep to hold moisture and acidity. Feed lightly after flowering with an acid-loving fertiliser — feeding before bloom pushes leaves at the expense of flowers. Never cultivate deeply around them; azalea roots are shallow.
Common problems
Lace bugs stipple leaves in summer, worst on sun-stressed plants — shade and water are the prevention, horticultural oil for severe cases. Root rot in soggy ground and chlorosis in alkaline soil are the other complaints, and both are siting verdicts. Petal blight may spot flowers in wet springs; pick off affected blooms and improve air circulation. A yellow azalea in limey soil is a soil verdict, not a hunger verdict.
Harvest
No fruit harvest — the crop is the spring show and the dusk glow. Prune lightly after flowering if shaping is needed, and water faithfully through the bloom. White flowers show petal blight more plainly than pink ones in a wet spring, so pick off spotted blooms and give the shrub air — it is cosmetic, not fatal.
Nerdy fact: White flowers are white because they reflect all wavelengths of light — which is also why they are the most visible flowers to night-flying moths. A white azalea at dusk is not just pretty; it is a beacon, and the moths treat it accordingly.
Saving seeds
Mrs. G. G. Gerbing — ‘Gerbing’ in the trade — is the white Southern Indica azalea: huge, single, pure-white flowers, opening in spring on a vigorous evergreen shrub 6 to 8 feet tall and wide. White flowers in a shade garden do something no other colour does: they glow at dusk, when the garden is winding down and the gardener is actually outside to see it. Gerbing is the azalea for a moon garden, a shady entrance, or a pairing with pink Indicas that need a white neighbour to set them off. As a named cultivar it is kept true by cuttings, not by seed — seedlings would not hold the pure-white flowers. Plant in fall or spring in part shade — morning sun, afternoon shade — in rich, moist, well-drained, acidic soil amended with pine bark and compost, and mulch thickly with pine bark or pine needles. The full method is in the Saving seeds section of the Rhododendron guide.