Annabelle hydrangea is a cultivar of the species Hydrangea arborescens, also known as smooth or wild hydrangea. The plant is commonly grown for its large, white flower clusters that can reach up to 12 inches in diameter. Annabelle hydrangeas bloom during summer and fall, and are valued for their prolific blooms. Annabelle hydrangea plants are hardy in zones 3 through 9, making them easy to grow in most temperate regions.
Plant Annabelle hydrangeas during spring, summer or fall in a location that receives partial sunlight throughout the day. Spread a light 1-inch layer of organic compost over the planting site and use a garden tiller to incorporate it into the soil to increase fertility and drainage.
Spread a 2-inch layer of mulch over the soil surrounding Annabelle hydrangeas. Begin the layer 2 to 3 inches away from the stem of the plant to allow air circulation and room for growth. Replenish as often as necessary throughout the year.
Water the Annabelle hydrangea plant once per week to prevent the soil from drying out completely. Do not water on weeks that receive at least 2 inches of rain. Apply during the early morning so excess water can evaporate before temperatures drop in the evening.
Feed Annabelle hydrangeas twice per year, once in early spring before new growth begins and again in late summer. Use a balanced 10-10-10 NPK fertilizer. Apply following the manufacturer's directions for proper dosage.
Prune Annabelle hydrangea plants in late winter, just before new growth begins in the spring. Use pruning shears to cut off any dead or damaged limbs to keep the plant compact and reduce the chance of disease. Remove any flowers that are dead or faded to encourage the plant to form additional blooms.