Frilly raspberry-red flowers with white centers cover this evergreen in spring, the ruffled petal edges giving each bloom more texture than a smooth-petaled rhododendron. Rhododendron Holden's™ 'Raspberry Ruffles' grows 3 to 4 feet tall and wide in part sun, hardy from Zone 5 through Zone 8.
This is the most compact of the group and the one that takes the most sun, handling some afternoon exposure where the others want shelter from it.
The Holden's rhododendrons were selected for two things that matter more than flower color: bud hardiness that holds through Zone 5 winters, and foliage that resists the leaf spot and root troubles that shorten the life of many rhododendrons. They are sold under the WorryFree® label for that reason.
The large-leaf rhododendrons hold their foliage year-round rather than thinning like the small-leaved types. Below about 25 degrees the leaves droop and curl up, curling tighter the colder it gets, and they open again within hours once temperatures rise. It looks alarming the first winter and it is entirely normal, a water-conserving response rather than a sign of trouble.
The size suits a foundation bed or a smaller garden. Acidic soil is necessary, roughly pH 4.5 to 6.0, with good drainage and steady moisture. Mulch the shallow roots.