Rhododendron ‘Patty Bee’ (‘Yaku Fairy’ x R. fletcherianum) – This RHS Award of Garden Merit winner features wavy-edged lemon yellow blooms that emerge April through to May. These absolutely cover the dense green foliage below, which turns an attractive bronze-red during the winter. ‘Patty Bee’ grows 18″ high by 2′ wide. Hardy to zone 6.
Rhododendron impeditum – A very cold hardy species rhododendron from China that works well in rock gardens. It bears tiny purplish-blue flowers that absolutely smother the bluish-green foliage below from March to April. This sun tolerant species often lightly re-blooms in early autumn and makes a good bonsai specimen. Grows 18″ high. Hardy to zone 5.
Rhododendron ‘Elizabeth Hobbie’ (‘Essex Scarlet’ x R. forrestii) – An excellent German hybrid that produces abundant blood red flowers that cascade slightly from April to May. The rounded dark green leaves form a dense canopy, usually right down to the ground. ‘Elizabeth Hobbie’ is also a good choice for mass planting. Grows 30″ high by 30″ wide. Hardy to zone 6.
Rhododendron ‘Karin Seleger’ (R. impeditum x R.dauricum) – This Canadian hybrid of two species rhododendrons has produced a compact, sun tolerant plant that also withstands the summer heat. ‘Karin Seleger’ produces small violet-purple flowers from early April into May over bronze-green leaves. It grows 2′ high by 3′ wide and is hardy to zone 5.
Rhododendron campylogynum – This Asian species rhododendron is an RHS Award of Garden Merit winner and bears unique nodding bell-shaped blooms that are waxy in appearance. They are typically a rosy-purple but are quite variable, also producing creamy white, red, salmon and dark purple flowers. Grows 30″ high and wide. Zone 6.