Hydrangea ‘Penny Mac’ is a Hydrangea macrophylla cultivar known for its consistent flowering. This deciduous shrub provides vibrant blooms and lush foliage throughout the summer. Its adaptability and extended bloom period make it a popular choice for various landscape designs.
Key Characteristics of Hydrangea Penny Mac
‘Penny Mac’ reblooms on both old and new wood, ensuring an extended display of blooms from June through September. New buds continue to set even if late frosts damage early ones, providing continuous color.
The flower color of ‘Penny Mac’ changes based on the soil’s pH level. In acidic soil, with a pH below 5.5, the blooms typically appear blue. Conversely, in alkaline soil, with a pH above 6.0, the flowers will be pink. Between these pH ranges, a mix of colors, including purple, can emerge.
This hydrangea grows 4 to 6 feet tall and 3 to 6 feet wide, forming a rounded, multi-stemmed shrub. Its deep green leaves provide a pleasant backdrop for the large, mophead-style flower clusters. Its moderate size makes it suitable for hedges, mass plantings, or container gardening.
Planting and Ongoing Care
Site Selection and Soil Preparation
Select a location with partial sun, ideally receiving morning sunlight and afternoon shade, especially in hotter climates. Too much direct afternoon sun can scorch leaves. The soil should be rich, loamy, and well-drained. If your soil contains heavy clay, amend it with organic matter like compost to improve drainage and structure.
Watering Needs
Consistent moisture is necessary for ‘Penny Mac’ hydrangeas, particularly during establishment and dry periods. After planting, water regularly for about three weeks to help roots settle. Water deeply at the plant’s base, rather than overhead, to ensure moisture reaches the root zone and minimize fungal disease risk.
Mulch around the base helps retain soil moisture, regulate soil temperature, and suppress weeds. During hot, dry weather, water every two to three days; cooler months require less frequent watering.
Fertilizing
Fertilize ‘Penny Mac’ hydrangeas in early spring as new growth begins. A balanced, slow-release fertilizer is recommended. Avoid over-fertilizing, especially with high-nitrogen formulas, as this can encourage leafy growth at the expense of flower production. To influence bloom color, use low-phosphorus options for blue blooms, or higher phosphorus formulations for pink flowers. Always follow product instructions carefully.
Winter Protection
‘Penny Mac’ is hardy in USDA Zones 5 through 9. In colder areas, particularly Zone 5, provide winter protection to preserve flower buds for the following season. Mulch around the base insulates roots. In exposed locations, loosely wrap the shrub in burlap for protection from harsh winds and freezing temperatures.
Pruning Hydrangea Penny Mac
When to Prune
Since ‘Penny Mac’ blooms on both old and new wood, its pruning requirements are less restrictive. The ideal time to prune is late winter to early spring, just before new growth emerges. Pruning immediately after the first flush of blooms also encourages subsequent flowering. Avoid heavy pruning during the active blooming season to prevent removing developing flower buds.
How to Prune
‘Penny Mac’ hydrangeas require minimal pruning. The primary goal is to remove any dead, damaged, or weak stems. When deadheading spent blooms, cut just above the next healthy set of leaves or buds. This encourages new growth and additional blooms.
Light shaping maintains the plant’s desired size and form, but severe cutting back is unnecessary and can reduce the bloom count. Leaving some spent blooms over winter protects dormant buds in colder climates.
Addressing Common Issues
‘Penny Mac’ hydrangeas are generally robust, but issues can arise. A lack of blooms may result from improper pruning or late spring frosts damaging buds. Ensure adequate sunlight and avoid excessive nitrogen fertilizer to promote prolific blooming.
Yellowing leaves often indicate nutrient deficiencies, such as iron chlorosis, or soil moisture issues. Overwatering, poor drainage, or too much direct sun can lead to root problems and leaf discoloration. Adjust watering practices and ensure well-drained soil to mitigate these problems.
‘Penny Mac’ hydrangeas are pest-resistant but can attract aphids, scale insects, or spider mites. Diseases like powdery mildew, root rot, or leaf spot may also occur. Promote good air circulation and avoid overhead watering to prevent fungal diseases. Address pest issues with appropriate treatments like insecticidal soap.