Bloomstruck Hydrangea Plant Profile

New and Improved "Endless Summer" Hydrangea

Closeup of purple blooms on Bloomstruck hydrangea plant.

Jennifer Blount / Getty Images

Bloomstruck hydrangea belongs to the "bigleaf" category of hydrangea bushes. It is in this hydrangea category that the color of the flowers is famously determined by the pH level of the soil. Bloomstruck hydrangea is also part of the Endless Summer series. This series is popular because it has been touted as the "reblooming hydrangea." Bloomstruck hydrangea produces large (3.5 to 5 inches across), mophead-style flower heads. Also attractive are its reddish-purple branches and dark-green leaves.

Botanical Name Hydrangea macrophylla 'P11HM-11'
Common Names Bloomstruck hydrangea
Plant Type Deciduous shrub
Mature Size 3 to 4 feet high and 4 to 5 feet wide
Sun Exposure Prefers partial shade generally but can tolerate some sun under certain conditions
Soil Type Fertile, well-drained
Soil pH Below 5.5 for blue flowers, 5.5 to 6.5 for purple flowers, above 6.5 for reddish flowers
Bloom Time July and August
Flower Color Varies from reddish to violet-blue depending on the soil pH
Hardiness Zones  4 to 9
Native Area Hydrangea macrophylla is native both to Asia and to parts of the New World

How to Grow Bloomstruck Hydrangea

This is a plant that requires little maintenance, as long as you are not fussy about flower color. Pruning is not necessary other than for removing, dead, diseased, or winter-damaged branches, or to remove branches that are rubbing against each other or jutting out in a way that spoils the overall shape of the shrub.

Hydrangea macrophylla, as a class, does exhibit some susceptibility to plant diseases such as bacterial wilt, blight, leaf spot, and powdery mildew (although Bloomstruck hydrangea tends to have better resistance to powdery mildew than the overall species does). Instances of powdery mildew can be reduced through liberal spacing (which promotes better air circulation) and by avoiding overhead watering (place the nozzle of your garden hose down at soil level, instead, when watering).

For insect pests, aphids are the biggest problem. Inspect the undersides of the leaves faithfully in case aphids find their way to your plants. Spray with Neem oil as soon as you detect the presence of aphids.

Light

At the southern end of its range, grow Bloomstruck hydrangea in partial sun. In the North, you have more of a choice: It can tolerate full sun if you keep its soil evenly moist at all times; otherwise, grow it in partial shade.

Soil

Enrich the ground (and improve its drainage at the same time) by mixing in generous amounts of decomposed organic matter.

Water

The shrub has average water needs if grown in partial shade, especially in the North. Mulching will help the soil retain the moisture it needs.

Fertilizer

Fertilize this shrub annually with compost or manure tea.

Uses for Bloomstruck Hydrangeas

Bloomstruck hydrangeas work well in summertime hedges since they furnish the yard with excellent color when in bloom. If you do not mind sacrificing a bit of that landscaping color for some indoor color, snip off a few of the flower heads, as they make for good cut flowers. Bloomstruck hydrangeas can also be used in shrub borders along property lines, but, since they are deciduous, do not expect to get much privacy from them outside of the summer and fall seasons.

While Bloomstruck hydrangea has a showy enough flower head to be a good summertime specimen (including as an accent in foundations plantings), you will achieve a greater impact with it in mass plantings.

Controlling the Color of Bloomstruck Hydrangeas

The color of the flowers will range from reddish in alkaline soil to violet-blue in acidic soil:

  • If you like the look of reddish flowers and are not getting them, add lime to the soil to achieve a more alkaline soil.
  • But if you want blue flowers and do not get them, it is aluminum sulfate that you should be adding to the soil to make it a more acidic soil.
  • A purplish color will result if your soil is somewhere in between in soil pH.

What Makes Bloomstruck Hydrangea Special

Bloomstruck hydrangea is valued as a reblooming (also called "remontant") hydrangea. It achieves this by being both a shrub that flowers on old wood and a shrub that flowers on new wood. In this regard, it is an improvement on the original Endless Summer hydrangea. The latter was touted as being reblooming failed to live up completely to its billing.