Hydrangea ‘Ocean’, a popular cultivar of Hydrangea macrophylla, is admired for its striking color variations and compact growth. This plant adds vibrant hues of blue, pink, or purple to gardens, making it versatile for landscape design.
Understanding Hydrangea ‘Ocean’
Hydrangea ‘Ocean’ matures to a size of 3 to 4 feet in both height and width, forming a dense, rounded shrub. Its large, rounded flower clusters, known as mopheads, can measure between 6 to 8 inches in diameter. These abundant blooms emerge in soft pink, later settling into a darker pink and creamy white, and can even develop lime green edges as they age.
The dark green foliage provides a lush backdrop for the colorful blooms. Like other Hydrangea macrophylla cultivars, ‘Ocean’ changes flower color based on soil pH. In acidic soils (below pH 6), flowers are blue or violet-blue. In alkaline soils (above pH 7), they are pink or red. A neutral to slightly acidic pH (5.5-6.5) can result in purple or mixed colors. This variation is influenced by aluminum availability, which is absorbed more readily in acidic conditions.
Planting and Cultivation
Selecting the proper planting site is important for Hydrangea ‘Ocean’. It thrives in locations with morning sun, protected from intense afternoon heat, as excessive direct sunlight can stress the plant. The ideal soil should be well-draining and rich in organic matter, providing a hospitable environment for root development. Average garden soil suits its needs.
Before planting, test the soil pH, especially if a specific bloom color is desired. For blue flowers, the soil pH needs to be acidic (below 6.0), achievable with amendments like elemental sulfur or aluminum sulfate. To encourage pink blooms, the soil should be more alkaline (above 7.0), and lime can be incorporated to raise the pH. Dig the planting hole at least twice as wide as the root ball and just as deep. After placing the plant, backfill with amended soil and water thoroughly to settle the soil.
Ongoing Care
Consistent moisture is important for Hydrangea ‘Ocean’, particularly during dry spells, as it requires moist but well-drained soil to thrive. Deep watering, rather than frequent shallow watering, encourages the development of a robust root system. Applying a layer of organic mulch, such as shredded bark or compost, around the base of the plant helps to retain soil moisture and regulate soil temperature.
Consider fertilization for general plant health and desired flower color. A balanced slow-release fertilizer supports overall growth. For blue flowers, use fertilizers low in phosphorus, as high phosphorus levels hinder aluminum uptake. For pink blooms, a high-phosphorus fertilizer can be beneficial. Pruning ‘Ocean’, which blooms on both old and new wood, involves removing spent flowers immediately after their bloom cycle to encourage new flushes. Remove any dead, damaged, or weak wood in late winter or early spring before new growth appears.
In colder climates, providing winter protection helps ensure the plant’s survival and future blooms. After the ground freezes, applying a 3 to 4-inch layer of mulch around the base of the plant insulates the roots from extreme cold. In regions experiencing severe cold snaps or prolonged freezing temperatures, covering the plant with burlap or a frost cloth can offer additional protection to the stems and dormant flower buds. Ensure the plant is well-hydrated before winter sets in.
Common Problems and Solutions
While generally vigorous, Hydrangea ‘Ocean’ can encounter issues. A common concern is lack of blooms, which can stem from improper pruning, especially if too much old wood (where some flower buds form) is removed at the wrong time. Late spring frosts can also damage tender new buds, preventing flowering. Ensuring adequate light, particularly morning sun, is important for bloom production.
Yellowing leaves may indicate chlorosis, a nutrient deficiency often related to soil pH affecting nutrient uptake, or overwatering. Improving soil drainage and adjusting pH to optimize nutrient availability can help. Browning leaf edges signal underwatering or heat stress, necessitating more consistent and deep irrigation during hot, dry periods.
Pests such as aphids and spider mites can affect Hydrangea ‘Ocean’. Aphids are small, green or black insects that cluster on new growth, while spider mites cause stippling on leaves and fine webbing. A strong water spray can dislodge aphids, and insecticidal soap manages both pests. Common diseases include powdery mildew, appearing as a white coating on leaves, and various leaf spots, which manifest as dark or discolored areas. Ensuring good air circulation, avoiding overhead watering, and removing affected leaves can help prevent and manage these fungal issues.