The ‘Ruby Slippers’ Hydrangea (Hydrangea quercifolia ‘Ruby Slippers’) is a compact deciduous shrub, celebrated for its oakleaf foliage and seasonal color changes. Developed by the U.S. National Arboretum, this hybrid combines traits of ‘Snow Queen’ and ‘Pee Wee’ oakleaf hydrangeas. Its large, conical flower clusters emerge creamy white in early summer, gradually transitioning to soft pink, and ultimately maturing to a deep, luxurious rose-red hue. Beyond its attractive blooms, the deep green, oak-shaped leaves transform into rich shades of burgundy, red, and mahogany in autumn, providing extended visual interest.
Planting and Establishing Ruby Slippers Hydrangea
Establishing ‘Ruby Slippers’ Hydrangea begins with site selection and soil preparation. It performs best with 2 to 6 hours of direct morning sunlight daily, ideally with afternoon shade to protect it from intense heat. While it tolerates full sun in cooler climates, too much shade can reduce fall foliage color. It thrives in organically rich, well-drained soil that remains consistently moist but not waterlogged, preferring a pH between 5.0 and 6.0 (slightly acidic to neutral). For heavy clay, amending with organic matter like compost improves drainage and aeration.
Dig a hole as deep as the root ball and at least twice as wide. Gently loosen any circling roots before placing the plant, ensuring the top of the root ball is level with or slightly above the surrounding ground. After backfilling with excavated soil, water thoroughly to settle the soil and eliminate air pockets. Consistent, deep watering during the first growing season is important for developing a strong root system.
Ongoing Care Essentials
Watering
Consistent moisture is important. While established plants show some drought tolerance, they perform best in moderately moist soil. Allow the top 2 inches of soil to dry out between watering sessions to prevent overwatering, which can lead to leaf blight or powdery mildew. Deep watering encourages a robust root system, and during dry spells or high heat, increase watering frequency to maintain plant health.
Applying a layer of organic mulch, such as shredded bark or pine needles, around the plant helps retain soil moisture, regulate soil temperature, and suppress weeds.
Fertilizing
‘Ruby Slippers’ Hydrangea does not require heavy fertilization. A light application of a balanced, slow-release granular fertilizer (e.g., 10-10-10) in early spring, and possibly again in mid-summer, can support growth and bloom production. Over-fertilization, particularly with nitrogen-heavy formulas, promotes leafy growth at the expense of flowers. If soil is alkaline, an acid-loving fertilizer may be beneficial.
Pruning and Bloom Management
‘Ruby Slippers’ Hydrangea blooms on old wood, with flower buds forming on the previous year’s growth. This influences pruning timing, and minimal pruning is needed for this compact shrub.
The best time to prune is immediately after the plant finishes blooming in early to mid-summer. This allows the plant to set new flower buds for the following year. Avoid pruning in late summer, fall, or winter, as this removes developing flower buds and reduces the next season’s bloom. Pruning involves removing dead, damaged, or weak branches in early spring. Deadheading spent blooms can be done for aesthetic reasons, but is not necessary for plant health.
Winter Protection and Troubleshooting
‘Ruby Slippers’ Hydrangea is hardy in USDA Zones 5 through 9. In colder parts of its range, particularly Zone 5, providing winter protection helps safeguard flower buds from temperatures below -10 degrees Fahrenheit. A protective layer of mulch around the base insulates roots and retains soil moisture during winter. For container-grown plants in colder zones, moving them to a sheltered, unheated space like a garage offers additional protection.
While ‘Ruby Slippers’ is known for its hardiness, it can experience minor issues. Pests like aphids and spider mites may appear, especially in dry conditions. A strong spray of water can dislodge these pests, or insecticidal soap can be used for persistent infestations. Leaf blight or powdery mildew can occur in overly moist conditions; ensuring good air circulation and avoiding overhead watering helps prevent these fungal problems. Removing affected foliage also helps manage these issues.