Best grown in acidic, humusy, organically rich, medium moisture, moisture-retentive but well-drained soils in part shade. Prefers a sun dappled or high open shade. Tolerates a fair amount of sun in cool northern summers, but leaves may scorch in hot afternoon sun in the St. Louis area. Plant in a location protected from strong winter winds. Good soil drainage is essential (doesn’t like “wet feet”). Poor drainage inevitably leads to root rot, therefore raised beds/plantings should be considered in heavy clay soils such as those present in much of the St. Louis area. Shallow, fibrous root systems (do not cultivate around plants) will benefit greatly from a mulch (e.g., wood chips, bark or pine needles) to help retain moisture and stabilize soil temperatures. Roots must never be allowed to dry out. Acidify soils as needed. Clip off spent flower clusters immediately after bloom as practicable. This azalea is not reliably winter hardy throughout USDA Zone 5.
‘Delaware Valley White’ is an evergreen azalea whose hybridization is unknown. It typically grows to 3-4’ tall over the first 10 years. Tubular, funnel-shaped, usually single, white flowers (to 2.5” across) bloom in clusters in early mid-season (late April-May). Each flower has 10 stamens. Obovate to oblong green leaves (to 1 1/4”long) usually turn yellow over winter. Some authorities list this cultivar as a Glenn Dale hybrid.
Rhododendrons and azaleas are susceptible to many insect and disease problems, including but not limited to canker, crown rot, root rot, leaf spot, rust, powdery mildew, aphids, borers, lacebugs, leafhoppers, mealybugs, mites, nematodes, scale, thrips and whitefly. A healthy plant in the proper environment with proper care should have limited problems, however.
Mass, group or specimen. Shrub borders, mixed borders, woodland gardens and shade gardens. Also effective in foundation plantings or as a hedge.