Does My Hydrangea Tree Need a Lot of Sun?

Many hydrangeas will benefit from the added shade of a porch overhang.

Hydrangeas generally grow as large shrubs, but several types can be adapted to a small, single-trunk, flowering tree. The key to planting hydrangeas in the correct sites is to first understand the type of hydrangea plants. Four common hydrangeas include the panicle hydrangea (Hydrangea paniculata), oakleaf hydrangea (H. quercifolia), bigleaf hydrangea (H. macrophylla) and smooth hydrangea (H. arborescens). Each type requires different types of light ranging from full sun to full shade.

Light Conditions

In any landscape, the light conditions change as one moves about the space. It is important to understand how the sun provides light in the yard when selecting the proper site for planting hydrangeas. Areas that receive up to 10 hours of steady sunlight per day are defined as full sun areas. Light shade features shade from an overhanging structure or tree that filters the sun; plants may still receive between five and 10 hours of sun. Partial shaded areas receive between four and eight hours of sun, but it's rarely direct and is filtered through a tree canopy or shade of a building.

Panicle Hydrangea

Panicle hydrangeas thrive when planted in full sun to partial shade. The panicle hydrangea is the most sun loving of the hydrangea species. Plant in sunny areas of the garden, but choose areas with lots of morning or evening sunlight. Direct, afternoon sunlight can damage even the most hardy hydrangea types. The panicle is known for its clusters of white flowers that turn slightly pink in the summer and brown in the autumn. This larger hydrangea reaches a mature height between 10 and 15 feet and is hardy in U.S. Department of Agriculture planting zones 4 through 8.

Oakleaf Hydrangea

The oakleaf hydrangea is another hydrangea type known for its white flower clusters. Distinguish this hydrangea from the panicle by its size; the oakleaf only reaches a mature height between 3 and 6 feet. Like the panicle, the hydrangea thrives in full sun to partial shade conditions. It requires moist soil, so provide lots of water during hot, dry weather. This type is hardy in USDA zones 5 through 9.

Bigleaf Hydrangea

The bigleaf hydrangea grows best when planted in partially shaded conditions and may be damaged by excessive sun exposure. When planted in full sun, the bigleaf hydrangea requires constantly moist soil and watering. Another unique property of the bigleaf hydrangea is its ability to produce different flower colors based on soil pH. Highly acidic soil produces blue flower clusters and alkaline soil results in pink flowers. This hydrangea prefers a mild climate, hardy in USDA zones 6 to 9. It can survive in zone 5 with proper winter protection.

Smooth Hydrangea

The smooth hydrangea prefers partial to full shade conditions. It can survive in full sun only when provided with constant moisture. Like the panicle and oakleaf hydrangeas, the smooth hydrangea produces cloudlike clusters of white flowers. This hydrangea is one of the smaller types, most commonly grown as a shrub. It reaches a mature height between 3 and 5 feet. It's more winter hardy than the bigleaf hydrangea, growing well in USDA zones 4 through 9.

References

• Fine Gardening; Distinguishing Degrees of Light and Shade; C. Colston Burrell
• Alabama Cooperative Extension System: Hydrangeas
• University of Illinois Extension: Selecting Shrubs for Your Home: Panicle Hydrangea
• University of Illinois Extension: Selecting Shrubs for Your Home: Oakleaf Hydrangea
• University of Illinois Extension: Selecting Shrubs for Your Home: Smooth Hydrangea
• Missouri Botanical Garden: Kemper Center for Home Gardening: Hydrangea Macrophylla