Endless Summer® BloomStruck® Reblooming Hydrangea
Vivid Flowers and Red Stems
Pink or purple-blue flowers top this heat and disease resistant hydrangea.
The Endless Summer® BloomStruck® Reblooming Hydrangea (Hydrangea macrophylla ‘PIIHM-II’) is a cultivated variety of the bigleaf hydrangea, a deciduous shrub from Asia belonging to the Hydrangeaceae family. BloomStruck® is part of the Endless Summer® collection of reblooming hydrangeas, and was introduced to the market in 2014 after six years of cultivation and testing. It stands apart for having saturated rose-pink or purple-blue flowers, striking foliage, and the ability to rebloom throughout the summer.
BloomStruck® is a rounded, spreading shrub with large mophead flowers in shades of rose-pink or purple-blue, depending on the pH of the soil. Flowers bloom all summer long on top of strong ruby red stems, and the leaves are a glossy dark green with showy red veins and petioles. It is a moderately fast growing hydrangea, adding 13 - 24 inches of growth per year until it reaches a mature size of 3 - 4 feet tall and 4 - 5 feet wide. Like all hydrangeas in the Endless Summer® Collection, BloomStruck® has the ability to bloom on both old and new wood, flowering repeatedly from late spring through fall despite extreme winter cold snaps and unpredictable spring freezes. It has above average heat tolerance and an increased disease resistance, especially to powdery mildew.
The BloomStruck® hydrangea grows in zones 4 - 9 and prefers partial shade and rich, well-draining soil (winter protection is recommended in zones 4 and 5). Partial shade is important, as these hydrangeas can be sensitive to intense sun exposure, particularly in the afternoon. In extreme heat, the large leaves of the bigleaf hydrangea can lose water quickly through transpiration, leading to wilting. A location with morning sun and dappled afternoon light is ideal for a BloomStruck® hydrangea. Deer will eat hydrangea flower buds and leaves, especially the tender young growth. If you would like to grow a flowering shrub that deer tend to leave alone, try Ruby Spice summersweet clethra as a deer resistant alternative to the bigleaf hydrangea.
What is a Reblooming Hydrangea?
A reblooming hydrangea blooms on both old and new wood, giving it the ability to produce flowers repeatedly throughout the growing season. The BloomStruck® hydrangea produces its first flush of blooms from buds that were set in the previous year; subsequent flowers emerge later in the summer from buds that form on the current season’s growth. Reblooming hydrangeas are also called remontant hydrangeas.
Although there was initial enthusiasm surrounding the debut of reblooming hydrangeas in 2004, many gardeners were left feeling disappointed as they failed to meet expectations. Subsequent advancements in hydrangea breeding have led to increasingly positive outcomes. BloomStruck® is part of a new generation or reblooming hydrangeas - years of selective breeding have resulted in a plant that reliably delivers on the promise of consistent, abundant blooms. It can handle cold winter temperatures and extreme heat, and still be able to reliably bloom the following year, raising the benchmark for reblooming hydrangeas varieties.
The striking purple-red stems of the Endless Summer® BloomStruck® Reblooming Hydrangea. Image credit: Bailey Nurseries
How to Plant and Grow BloomStruck® Reblooming Hydrangea
Planting: The best time of year to plant a BloomStruck® hydrangea is in the spring or fall, giving the roots time to establish before the onset of extreme hot or cold weather. Water deeply immediately after planting. BloomStruck® is an extremely popular hydrangea and has a tendency to sell out quickly, so visit the nursery in early spring for the best selection!
Location: Choose a location with well-drained soil that is rich in organic matter. BloomStruck® prefers soil that retains moisture but does not become waterlogged. Select a spot with partial shade and protection from the intense afternoon sun.
Soil: Amend the soil with organic matter such as compost, shredded leaves, or Leaf-gro® to improve drainage and soil fertility. If you want BloomStruck® to take on either vivid rose-pink or purple-blue hues, consider getting a soil test and adding sulfur or lime to the soil. Add sulfur for a purple-blue tinge and lime for a blush of pink.
Mulch: Apply a layer of organic mulch around the base of the plant to retain soil moisture, regulate temperature, and suppress weeds. Make sure the mulch does not touch the base of the plant.
Watering: Keep the soil consistently moist but not waterlogged, especially during periods of drought. Deep watering is preferable to encourage the development of a strong root system (Are you in a drought? Check the U.S. Drought Monitor).
Fertilization: Hydrangeas typically do not need fertilization when they are given the rich, fertile soil they prefer. Each spring, spread a layer of compost, shredded leaves or Leaf-gro® around the base of your hydrangea, being careful to keep away from the base of the shrub.
Pruning: BloomStruck® hydrangeas require little to no pruning - if you prune too much, you risk cutting off buds that will eventually become flowers. In spring, cut out dead canes once new growth has emerged. If you must prune back a BloomStruck® hydrangea for size, cut back by no more than half in late summer.
Pest and Diseases: BloomStruck® hydrangeas have improved disease resistance. They may occasionally suffer from aphids or spider mites. Ensure good air circulation around your plants to minimize the risk of disease, and practice good watering habits (see “How to Water your Plants” to brush up on your watering skills).
Do BloomStruck® Hydrangeas Like Sun or Shade?
The BloomStruck® Reblooming Hydrangea thrives in partial shade (2 - 4 hours of direct sunlight per day). BloomStruck® prefers morning sun and dappled or filtered afternoon shade. This hydrangea does best with protection from the intense rays of the afternoon sun, particularly in hotter climates.
Planting Companions for BloomStruck® Reblooming Hydrangea
Feeling inspired to plant a BloomStruck® hydrangea in your garden? Here are some ideas for planting companions - all favor the same partial shade conditions and moist, rich, well-draining soil that bigleaf hydrangeas love:
Shrubs:
Himalayan Sweet Box (Sarcococca hookeriana var. humilis): A low-growing evergreen ground cover for the shade. Its glossy dark green leaves are the perfect complement for a BloomStruck® hydrangea.
NewGen Freedom® Boxwood (Buxus NewGen Freedom® ‘SB 300’): The small leaves and structured shape of boxwoods are the perfect evergreen companion for bigleaf hydrangeas. NewGen Freedom® boxwoods have a uniform, tight rounded habit and improved resistance to boxwood leafminer.
Perennials:
Garnet Tickseed (Coreopsis ‘Garnet’): This low-growing perennial is covered with small, deep garnet red flowers that complement the red stems of the BloomStruck® hydrangea.
Astilbe (Astilbe spp.): The fine textured foliage and spiky summer flowers of astilbe are a great partner for BloomStruck® hydrangeas. Purple or red varieties like ‘Montgomery’ or ‘Black Pearls’ look particularly nice.
Variegated Solomon’s Seal (Polygonatum falcatum ‘Variegatum’): This slow-growing perennial with variegated leaves and arching stems pairs nicely with the BloomStruck® hydrangea.
Jack Frost Siberian Bugloss (Brunnera macrophylla ‘Jack Frost’): The silvery-green foliage and airy blue flowers of this shade-loving perennial contrast with the glossy dark green leaves of BloomStruck®.
Japanese Painted Fern (Athyrium niponicum 'Pictum'): Dramatic blue-green-silver foliage and a short stature make this fern a great choice to use as a facer plant in front of BloomStruck®.
Landscape Design Ideas for BloomStruck® Reblooming Hydrangea
Foundation Planting: Plant BloomStruck® hydrangeas along side the foundation of your house. Their bright, vivid flowers and glossy green foliage will enhance the curb appeal of your home.
Mixed Borders: Create a mixed border planting by combining BloomStruck® with other complementary perennials, ornamental grasses, deciduous and evergreen shrubs for four seasons of color and texture.
Mass Planting: Plant BloomStruck® hydrangeas in groupings to create a mass of color. This approach works well in large garden beds or alongside pathways and fences, providing a striking visual impact.
Woodland Garden: The dappled shade underneath the canopy of tall trees is an ideal spot for a BloomStruck® hydrangea. Combine with other partial-shade loving plants like camellias, Japanese andromeda, azaleas, and rhododendrons.
Accent Planting: Use BloomStruck® as a focal point in the landscape. Plant strategically to draw attention to specific areas of the garden, like entryways, water features, pathways, seating areas, or garden sculptures.
Containers: With its saturated flower colors and vivid foliage, BloomStruck® is a natural fit for decorative pots and planters. Pair with spillers like sweet potato vine and trailing lobelia.
Are BloomStruck® Reblooming Hydrangeas Poisonous to Dogs?
BloomStruck® Reblooming Hydrangeas (Hydrangea macrophylla ‘PIIHM-II’) contain compounds that can be toxic to dogs if ingested, specifically cyanogenic glycosides. These compounds can release cyanide when broken down in the digestive system. However, the level of toxins in bigleaf hydrangeas are relatively low, and instances of dogs getting poisoned by consuming these plants are rare.
While the risk of severe poisoning is low, it’s important to monitor your dog's behavior in outdoor spaces. If you suspect your dog has ingested a toxic plant, seek immediate veterinary care or contact the Pet Poison Hotline (read “Which Plants are Toxic to Dogs” for more information on plants poisonous to dogs).
Why isn’t my BloomStruck® Hydrangea Blooming?
It can be quite disappointing when your hydrangea fails to bloom, especially when you've been eagerly anticipating its striking white flowers. Several factors could contribute to its lack of blooms:
Improper pruning: Did you prune your BloomStruck® hydrangea? You may have cut off flower buds that would eventually become flowers. This hydrangea requires little to no pruning. Never hard prune a BloomStruck® hydrangea, and never prune in the fall or you will risk losing future blooms.
Young plant: Hydrangeas may take a few years to establish before they start blooming. If your plant is still relatively young, it might just need more time to mature and establish itself - be patient!
Insufficient sunlight: For best flowering, BloomStruck® hydrangeas need at least 2-4 hours of direct sunlight per day. If they're not getting enough sunlight, they may produce fewer blooms or fail to bloom altogether.
Watering issues: Inconsistent or inadequate watering can stress the plant and affect flowering. Ensure your hydrangea receives sufficient water, especially during hot and dry periods.
Deer: Deer like the taste of hydrangeas, particularly the flowers and buds. They may visit your yard and nibble the buds off of your hydrangea, leaving no evidence of their presence other than the absence of flowers.