How to Fertilize Rhododendron 'Wilgen's Ruby'?
Ericaceous fertilizer monthly from spring through late summer

Rhododendron 'Wilgen's Ruby' · Rhododendron 'Wilgen's Ruby'
Grow in light dappled shade, in a site sheltered from cold, dry winds and late frosts, in moist but well-drained, humus-rich, acidic soil, preferably between pH4.5 and pH5.5; will also tolerate sun and dry soil; for more advice, see rhododendron cultivation
Ericaceous fertilizer monthly from spring through late summer