Hydrangea Care Guide: Growing Gorgeous Blooms
Hydrangeas are beloved garden shrubs, famous for their large, showy flower heads that provide stunning color from summer through fall. With several distinct types available, understanding which one you have is crucial, especially when it comes to pruning, as this determines whether flowers form on old or new wood. From the color-changing Bigleaf hydrangeas to the cone-shaped blooms of Panicle types, there's a hydrangea for almost any garden.
Common Types of Hydrangeas
Understanding the main groups is key, especially for pruning:
Bigleaf Hydrangea (H. macrophylla)
- Includes Mopheads (large, round clusters) and Lacecaps (flat clusters with fertile center/showy outer flowers).
- Blooms on old wood (last year's stems). Some newer varieties (e.g., Endless Summer® series) bloom on both old and new wood.
- Flower color (pink/blue) influenced by soil pH (acidic=blue, alkaline=pink) for most cultivars (whites stay white).
- Prefers morning sun, afternoon shade, and consistent moisture.
- Pruning: Prune after flowering (mid-summer) only if needed to shape or remove dead wood. Avoid late fall/winter/spring pruning which removes flower buds. Rebloomers can be pruned more liberally.
Panicle Hydrangea (H. paniculata)
- Cone-shaped flower clusters, often starting white and aging to pink/red. Blooms on new wood (current season's growth).
- Most sun-tolerant type; can handle full sun in many regions. Upright, sometimes tree-like growth.
- Examples include: 'Limelight', 'Little Lime', 'Vanilla Strawberry', 'Quick Fire'.
- Pruning: Prune in late winter/early spring before new growth begins. Can be cut back significantly (by 1/3 to 1/2) to encourage strong stems and large flowers.
Smooth Hydrangea (H. arborescens)
- Native US species, known for large, round white (sometimes pink) flower heads. Blooms on new wood.
- Tolerates more shade than Panicle types. Stems can be floppy.
- Examples include: 'Annabelle', 'Incrediball', 'Invincibelle Spirit'.
- Pruning: Prune hard in late winter/early spring, cutting stems back to 6-12 inches. This encourages sturdy new growth.
Oakleaf Hydrangea (H. quercifolia)
- Distinctive oak-shaped leaves offering excellent fall color (red/burgundy). Cone-shaped white flowers aging to pink. Blooms on old wood.
- Tolerates more shade; good for woodland settings. Peeling bark adds winter interest. Native to the Southeastern US.
- Pruning: Prune after flowering only if needed for shaping. Avoid removing stems in fall/winter/spring.
Planting Hydrangeas
Proper site selection and planting technique are important for these shrubs.
When to Plant
- Spring or Fall: Best times, allowing roots to establish before summer heat or winter cold.
Ideal Growing Conditions
- Light: Morning sun and afternoon shade is ideal for most, especially Bigleaf hydrangeas. Panicle hydrangeas tolerate full sun best. Oakleaf and Smooth hydrangeas handle more shade.
- Soil: Rich, moist, but well-draining soil. Amend with compost. While they like moisture, they hate waterlogged conditions.
- Soil pH (for Bigleaf): To influence blue/pink color:
- Blue: Acidic soil (pH 5.5 or lower). Amend with soil acidifiers like aluminum sulfate or elemental sulfur.
- Pink: Alkaline soil (pH 6.5 or higher). Amend with garden lime.
- Color change takes time and repeat applications may be needed. Soil test recommended.
- Spacing: Allow ample room for mature size (3-10+ feet depending on type). Ensure good air circulation.
Planting Technique
Select a location with appropriate light and well-draining, amended soil.
Dig a hole 2-3 times wider than the root ball and just as deep.
Gently remove the hydrangea from its pot. Loosen circling roots. Place in the hole so the top of the root ball is level with or slightly above the surrounding soil.
Fill the hole with amended soil, gently firming around the base. Water thoroughly to settle the soil.
Apply a 2-3 inch layer of organic mulch (bark, shredded leaves) around the base, keeping it away from the stems, to conserve moisture and regulate soil temperature.
Watering Hydrangeas
- Hydrangeas, especially Bigleaf types, need consistent moisture. The name "Hydra" even refers to water!
- Water deeply whenever the top few inches of soil feel dry. Wilting leaves are a clear sign they need water.
- Provide about 1 inch of water per week during the growing season, more during hot, dry spells or if planted in full sun.
- Water at the base of the plant to keep foliage dry and reduce disease risk.
Fertilizing Hydrangeas
- Fertilize lightly in early spring with a balanced, slow-release fertilizer formulated for shrubs or trees.
- A second light application in early summer can be beneficial, especially for reblooming types.
- Avoid excessive nitrogen, which promotes leaves over flowers.
- For influencing color in Bigleaf types, use specific pH-adjusting fertilizers or amendments rather than general-purpose ones.
Products labeled "Color Me Pink" (containing lime) or "Color Me Blue" (containing aluminum sulfate) are available specifically for adjusting Bigleaf hydrangea flower color. Follow package directions carefully.
Troubleshooting Common Problems
Lack of Blooms
Possible Causes and Solutions
- Improper Pruning: Pruning at the wrong time (especially for old-wood bloomers like Bigleaf/Oakleaf) removes flower buds. Know your type and prune accordingly!
- Winter Damage/Late Frost: Buds on old-wood bloomers can be killed by cold winters or late spring frosts. Protect plants in cold zones or choose hardier types (Panicle, Smooth) or reliable rebloomers.
- Too Much Shade: Most need at least 4-6 hours of sun (preferably morning sun) for good flowering.
- Too Much Nitrogen Fertilizer: Encourages leaf growth over flowers. Use a balanced or low-nitrogen fertilizer.
- Plant is Young: May take a year or two to establish and bloom well.
- Deer Browsing: Deer may eat flower buds.
Diseases (Powdery Mildew, Leaf Spot)
Symptoms and Management
- Powdery Mildew: White coating on leaves. Common in humid conditions with poor air circulation.
- Leaf Spot (Cercospora, Anthracnose): Fungal spots on leaves, often more prevalent later in the season.
- Prevention/Control: Ensure good air circulation (proper spacing, selective pruning). Water at the base, avoid wetting foliage. Clean up fallen leaves in autumn. Choose resistant varieties. Fungicides (horticultural oil, copper-based) can be used preventatively or at first sign of disease. Leaf spot is often cosmetic and doesn't severely harm established plants.
Conclusion
Hydrangeas offer magnificent blooms and considerable garden presence. Success lies in choosing the right type for your climate and location, understanding its specific pruning needs (old wood vs. new wood!), providing consistent moisture, and ensuring good air circulation. With proper care, these stunning shrubs will reward you with a spectacular floral display year after year.
