Rhododendron ‘English Roseum’ (sport of ‘Roseum Elegance’) – A large-growing Rhododendron cultivar which makes an excellent informal hedge, much in part to its dense growth habit. It features trusses of lavender-pink flowers emerging from purplish-buds, with some light yellow spotting on the blooms. Generally flowers in May. Grows 6-8′ high and wide. Hardy to zone 5.
Rhododendron ‘Ilam Violet’ (R. augustinii ‘Electra Group’ x R. russatum) – This rhododendron makes up for its smaller April to May trusses with intense deep violet-blue flowers that really catch the eye. The thin dark green leaves also turn a bronze colour during the colder winter weather. This 1947 introduction requires good soil drainage. Grows 4-6′ high by 4′ . Zone 6.
Rhododendron catawbiense ‘Boursault’ – The large trusses of lavender blooms (emerging from violet buds) are nicely accented with light orange spotting. It is another hardy, easy to grow Rhododendron which is a consistent performer in colder regions. ‘Boursault’ also features mid green foliage that is sun tolerant with even soil moisture. Grows 5-8′ high and wide. Zone 5.
Rhododendron ‘Edith Bosley’ (‘Dexter’s Bosley #1035’ x ‘Lee’s Dark Purple’) – ‘Edith Bosley’ bears ruffled dark reddish-purple blooms (usually in May) that are hard to miss in any garden. It is extremely cold hardy and has attractive deep green foliage. This Rhododendron is considered to be an improvement of ‘Purple Splendor’. Grows 4′ high and wide. Hardy to zone 4 (with shelter).
Rhododendron ‘Bariton’ (‘Arthur Bedford’ x ‘Purple Splendor’) – This German hybrid by Hans Hachmann bears large rounded trusses of violet-purple flowers with strong burgundy-red spotting and white-stemmed stamens. It blooms from mid to late spring over pointed, deep green foliage. Prefers a part sun exposure. Grows 5-7′ high by 4-6′ wide. Hardy to zone 6.