Rhododendron austrinum hybrid "Stonewall Jackson"

Large trusses of big yellow flowers with reddish tubes and red to pink tones

Light Requirements: Prefers partial shade to full sun. Rhododendron austrinum thrives best in partial shade, especially in hotter climates, where some protection from the intense afternoon sun can help prevent leaf scorch and stress. It can tolerate full sun, particularly in cooler regions, which can promote more prolific blooming.

Soil Requirements: Prefers well-draining, acidic soil. This azalea grows best in rich, loamy soil with a pH range of 4.5-6.0. It is essential that the soil is well-draining to prevent root rot, as this plant does not tolerate waterlogged conditions. Adding organic matter, such as compost, peat moss, or pine bark, will improve soil structure and increase acidity, supporting healthy growth.

Watering: Requires regular watering to maintain consistently moist soil. Rhododendron austrinum prefers evenly moist soil, especially during the growing season. While it can tolerate brief dry periods once established, it does not thrive in drought conditions. Mulching around the base of the plant helps retain moisture and keeps the roots cool.

Temperature and Humidity: Hardy in USDA zones 6-9. Rhododendron austrinum is well-suited to warm, humid climates, particularly in the southeastern United States. It can tolerate mild winters and is relatively cold-hardy, although protection may be needed in the coldest parts of its range. High humidity is beneficial, aligning with its natural habitat in moist, woodland areas.

Fertilization: Apply a balanced, slow-release fertilizer formulated for acid-loving plants in early spring. An additional light feeding in mid-summer can help sustain growth and flowering. Avoid over-fertilizing, as this can lead to excessive foliage growth at the expense of flowers and can also damage the roots.

Pruning: Prune lightly after flowering to maintain the plant’s shape and remove any dead or damaged branches. Rhododendron austrinum typically requires minimal pruning, as it naturally develops a pleasing shape. If necessary, prune in late winter or early spring before new growth begins, but avoid heavy pruning, which can reduce the following year’s blooms.

Pests and Problems: Generally pest-resistant but may occasionally be affected by common azalea pests such as lace bugs, spider mites, or aphids. Ensuring good air circulation around the plant and avoiding overhead watering can help prevent fungal diseases such as powdery mildew or root rot. If pests or diseases are detected, treat with appropriate measures such as insecticidal soap or fungicides.