Caring for Your Hydrangea


Description: With their big showy flowers, Hydrangeas are one of the most desirable ornamental shrubs for gardeners and landscapers alike. They are well suited for natural landscape settings and will always attract attention to the garden when they are in bloom.

They produce masses of eye-catching flowers in the mid-summer which lasts well into autumn. Today’s cultivars produce various flower colorations consisting of numerous hues of pink, rose blue, and white. The coloration of the flowers is greatly influenced by the acidic properties of the soil where they are growing. Plants growing in acidic soils tend to produce violet or blue flowers. Conversely, plants growing in alkaline soils tend to produce pink flowers.

Preferred Conditions: Hydrangea prefers to be planted in locations with moderately fertile, well-drained soils. They perform well in most soils as long as there is adequate moisture available. Locations with light to medium shade are best for most cultivars, but the H. macrophylla varieties can tolerate more direct sunlight. When they are grown under too much shade, they will not grow as vigorously and fewer flowers will be produced.

Planting & Maintenance: Hydrangea are easy to grow and require only a few routine maintenance activities. When planting, the top of the root ball should be level with the soil surface. Water them thoroughly after transplanting.

Most varieties form their flower buds in the late summer for the following year. They should only be pruned when the flower heads begin to fade, otherwise you’ll risk removing next year’s flowers. When pruning, remove spent flower heads and prune back other shoots to encourage branching and fullness.

Although the coloration of the flowers is influenced by the soil pH, it is actually the presence or absence of aluminum that affects flower coloration. If aluminum is present within the plant, the blooms will be blue and if it is absent, the flowers will appear pink. The pH influences the availability of aluminum for uptake by the plant. When the soil is acidic (pH around 5.5) aluminum is generally more available to the plant and blue flowers result. Conversely, when the soil is alkaline (pH near 7.0), the availability of aluminum is decreased which leads to the formation of pink flowers.

If blue flowers are desired, it may be advantageous to apply drenches of aluminum sulfate (one tablespoon per one gallon water) around the plant in the early spring. Avoid getting the solution on the leaves because foliar damage may result. If pink flowers are desired on Hydrangeas planted in acidic soils, it will be necessary to increase the pH by drenching the soil with hydrated lime (one tablespoon per on gallon water) in the early spring.

The application of 3 to 5 inches of organic mulches will help retain moisture and decrease the occurrence weeds throughout the growing season. Hydrangeas grow best if they are fertilized regularly. Regular additions of organic matter, such as organic mulches, will often suffice. Otherwise, a slow release, balanced fertilizer applied once or twice per year (in the late spring and mid-summer) will provide adequate nutrition.

Uses in the Garden: Hydrangea are commonly used as specimen plants or in mixed borders, open woodlands, and mass plantings.

Other Uses and Attributes: They are commonly used as cut flowers or in dried floral arrangements. Hydrangeas are easy to grow in containers and make great patio pots in outdoor living areas.

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