The pom pom hydrangea is a popular garden shrub, known for its distinct, spherical flower clusters. Its unique form and reliable blooming make it a favored choice, adding classic charm and visual impact to landscapes.
Key Features of Pom Pom Hydrangeas
Pom pom hydrangeas are recognized by their large, rounded flower heads, resembling snowballs or oversized pom-poms. These impressive flower clusters can reach diameters of 8 to 12 inches. While some varieties may begin with a lime green tint, the blooms typically mature to a pristine white, often transitioning to pale green or tan shades later in the season.
This shrub, commonly a cultivar of Hydrangea arborescens such as ‘Annabelle’, typically grows to a mature size of 3 to 5 feet tall with a similar or wider spread, forming a mounding, deciduous shrub. Its dark green, serrated leaves provide a lush backdrop for the abundant blooms, which generally appear from early summer and can continue to offer appeal into the fall.
Planting and Ongoing Care
For a thriving pom pom hydrangea, select the right location. These plants prefer partial shade, especially protection from intense afternoon sun in warmer climates, though they tolerate full sun with consistent moisture. Ideal soil is well-draining, rich in organic matter, and has a slightly acidic to neutral pH. Amending with compost improves structure and nutrient content.
When planting, dig a hole twice as wide as the root ball and just as deep. Position the plant so the top of the root ball is level with the surrounding soil. Backfill the hole with amended soil, gently firming it around the roots to remove air pockets. Water the plant thoroughly immediately after planting to help it settle.
Consistent watering is essential, particularly during establishment and dry periods. They prefer consistently moist soil but do not tolerate waterlogging. Signs of insufficient water include drooping leaves, while yellowing leaves or browning edges may indicate overwatering. Watering deeply at the base of the plant in the early morning is recommended to ensure moisture reaches the root system and to prevent fungal issues.
Fertilization benefits hydrangeas, though established plants in rich soil may require less. Apply a balanced, slow-release fertilizer (e.g., 10-10-10 NPK) in early spring as new growth emerges. A second application in mid-summer can support continued flowering, especially for varieties that bloom on new wood. Avoid fertilizing late in the growing season, as this can stimulate tender new growth that may be vulnerable to winter cold.
Pom pom hydrangeas are generally resistant to common pests and diseases. However, they can be susceptible to powdery mildew or leaf spots, particularly in humid conditions with poor air circulation. Ensuring good air circulation and watering at the base of the plant can help prevent these problems.
Pruning Techniques
Pruning maintains the health, shape, and abundant flowering of pom pom hydrangeas. Since these plants (Hydrangea arborescens types) bloom on new wood (current season’s growth), prune in late winter or early spring before new growth begins. This timing ensures that the flower buds, which form on the new shoots, are not removed.
To encourage robust blooms, prune the plant back significantly. Cutting stems back by one-half to one-third, or even down to 12 to 18 inches from the ground, can promote fewer but larger flower heads. Alternatively, less aggressive pruning or tip pruning can result in more numerous, though potentially smaller, flower heads. Always remove any dead, damaged, or weak branches.
If the plant tends to flop under the weight of its large blooms, pruning to a height of 18-24 inches rather than cutting it to the ground can help the stems thicken over time, providing better support. Placing a short wire fence or support around the plant early in the season can also help support heavy blooms.
Winterizing Your Hydrangea
Prepare your pom pom hydrangea for winter to ensure its survival and vigor. Root protection is important.
Apply a thick layer of mulch, such as wood chips or straw, around the base of the plant. This layer, typically 3 to several inches deep, insulates the roots from freezing and thawing cycles and helps retain soil moisture. For added protection in colder climates, especially where temperatures dip below -30 degrees Fahrenheit, a wire cage wrapped with burlap can be placed around the plant to shield it from harsh winds and heavy snow. Ensuring the plant is well-watered before the first hard frost also contributes to its winter hardiness.