Bigleaf hydrangea (Hydrangea macrophylla 'Grenan' NANTUCKET BLUE)
Explore Hydrangea macrophylla 'Grenan' NANTUCKET BLUE, a reliable reblooming Bigleaf hydrangea, 4-6ft tall, known for its mophead blooms shifting color by soil pH.
Scroll down to discover growing tips, care requirements, companion plants, and more
Complete Plant Information
Overview
The Hydrangea macrophylla ‘Grenan’ NANTUCKET BLUE is a distinguished cultivar of Bigleaf hydrangea, valued for its reliably reblooming nature. Unlike many hydrangeas, this variety develops flower buds on both old and new wood, ensuring a display of large, showy mophead blooms even after harsh winters. Its adaptability in color, shifting from vibrant blue in acidic conditions to soft pink in neutral soils, offers dynamic visual interest in the garden.
As a deciduous shrub, Hydrangea macrophylla ‘Grenan’ NANTUCKET BLUE offers a rounded habit, typically reaching 4 to 6 feet in height and spread. Gardeners appreciate this Bigleaf hydrangea for its substantial dark green foliage that beautifully contrasts with the long-lasting summer flowers. It serves both as an excellent structural element and a reliable source of summer color.
The NANTUCKET BLUE selection, part of the Garden Debut® brand, brings functional beauty as a hedge or specimen plant near patios. Successful cultivation relies on maintaining consistent moisture and monitoring soil pH to capture the desired flower hue. Integrating Hydrangea macrophylla ‘Grenan’ NANTUCKET BLUE into your landscape guarantees dependable summer performance for years to come.
Fast Facts
- Plant Family: Hydrangeaceae
- Plant Type: Deciduous shrub
- Hardiness Zones: USDA Zones 6-9
- Size at Maturity:
- Height: 4-6 ft
- Spread: 4-6 ft
- Bloom Time: July to August
- Bloom Description: Blue in acid soil and pink in neutral soil
- Sun Exposure: Part shade
- Water Needs: Medium
- Maintenance Level: Medium
How to Grow
Planting your Bigleaf hydrangea is best achieved in spring or fall in a location offering part shade protection, especially from intense afternoon sun. These shrubs thrive in rich, well-drained soils with medium moisture levels. While tolerant of some sun, inconsistent moisture in a full-sun location can stress the plant; aim for morning sun combined with afternoon shade for best results.
Watering should be consistent, as the name Hydrangea suggests (referring to “water”). Aim for medium water needs, ensuring the soil remains evenly moist but never waterlogged. Soil pH management is crucial for color selection: use aluminum sulfate to encourage deep blue flowers, or add lime to shift the blooms toward pink. Initiate these soil treatments in late autumn or early spring, well before the growing season begins.
Pruning needs for Hydrangea macrophylla ‘Grenan’ NANTUCKET BLUE are minimal due to its reblooming nature. If shaping is necessary, prune immediately after flowering by cutting stems back to a set of healthy buds. In late winter or early spring, remove any wood that appears damaged or weak from winter cold. Applying a 3-inch layer of organic mulch, such as shredded bark or compost, around the base helps retain soil moisture and moderate root temperatures year-round.
For gardeners in the colder end of its range (Zone 6), extra winter protection may be warranted. While the reblooming habit helps salvaged blooms, providing sheltered siting reduces the risk of die-back to the ground. Mulch heavily, but avoid excessive winter wrapping unless conditions are predicted to be extremely harsh, as these measures can be cumbersome.
Landscape Uses
The versatility of Hydrangea macrophylla ‘Grenan’ NANTUCKET BLUE makes it an excellent anchor in many garden designs. It excels when massed or grouped within a shrub border, creating a substantial block of mid-summer color. Its neat, rounded habit also lends itself perfectly to serving as an accent piece or specimen planting near entryways, patios, or foundations where its mophead flowers can be easily admired.
Consider using this Bigleaf hydrangea as a backdrop for shorter perennials that enjoy similar shade and moisture requirements, such as hostas, astilbes, or ferns. When planted loosely as a hedge, the 4 to 6-foot spread of Hydrangea macrophylla ‘Grenan’ NANTUCKET BLUE provides a soft, informal screen. It also performs well when given ample root space in large decorative containers near seating areas.
If your goal is to manipulate flower color, plant the NANTUCKET BLUE near structures that reflect light but do not intensify the mid-day heat. Grouping plants with similar needs simplifies watering routines and ensures that all components of the border benefit from the rich, well-drained soil structure preferred by this species.
Standout Features
Flower Qualities
- Showy
- Good Cut
- Good Dried
Noteworthy Characteristics
Hydrangea macrophylla, commonly called big leaf hydrangea, is a deciduous shrub with a rounded habit that, in the St. Louis area, typically grows 3-6’ tall and as wide unless damaged by harsh winters or pruned smaller. It generally features serrate, obovate to elliptic, dark green leaves (4-8” long) and large clusters of long-blooming summer flowers in either lacecap form or mophead form. ‘Grenan’ was introduced by Greenleaf Nursery under their Garden Debut® brand and is sold as NANTUCKET BLUE. It is a reblooming hydrangea that, because it develops flower buds on both old and new wood, will bloom even if flower buds are damaged by harsh winter cold.
Tolerances
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Potential Problems
This Bigleaf hydrangea cultivar demonstrates some susceptibility to common hydrangea issues, including bud blight, leaf spot, and mildew. Bacterial wilt is another potential concern if drainage is poor or the plant experiences significant stress. Aphids may occasionally visit the new growth but rarely cause lasting harm if populations remain low.
Prevention is the best defense against these fungal and bacterial problems. Ensure excellent air circulation around the stems by avoiding overly dense planting schemes and providing the recommended part shade. Water the base of the plant rather than overhead, particularly late in the day, to prevent moisture from lingering on the foliage, which encourages mildew and leaf spot development.
Frequently Asked Questions
What hardiness zones is Hydrangea macrophylla ‘Grenan’ NANTUCKET BLUE suitable for?
This reblooming Bigleaf hydrangea thrives in USDA Hardiness Zones 6 through 9. Gardeners in Zone 5 should provide extra winter protection to safeguard flower buds.
How large does Bigleaf hydrangea grow?
Hydrangea macrophylla ‘Grenan’ NANTUCKET BLUE typically reaches a mature height between 4 and 6 feet, with a corresponding spread of 4 to 6 feet, assuming no winter damage occurs.
When does Hydrangea macrophylla ‘Grenan’ NANTUCKET BLUE bloom?
This variety blooms throughout July and August. The color of these large mophead blooms is intrinsically linked to soil chemistry, appearing blue in acid soil and pink in neutral soil.
What sun exposure does Bigleaf hydrangea need?
This plant prefers part shade. It can handle full sun only if the soil is kept consistently moist throughout the growing season.
Conclusion
The Hydrangea macrophylla ‘Grenan’ NANTUCKET BLUE offers landscape reliability through its consistent, reblooming nature and attractive mophead structure. Controlling the soil pH allows you to customize the flower color, adding a layer of horticultural fun to its aesthetic value. Before planting, confirm your local USDA zone compatibility and prepare a rich, well-drained site to ensure this excellent Bigleaf hydrangea provides years of reliable summer color.
Companion Planting
Selecting companions for Hydrangea macrophylla ‘Grenan’ NANTUCKET BLUE should focus on plants that share its requirement for high moisture and partial shade. Excellent partners include plants that thrive in dappled light, such as various hostas, providing contrasting leaf textures. Ferns, particularly Japanese Painted Ferns or Ostrich Ferns, create a lush, woodland understory effect beneath the spreading canopy of the hydrangea.
If you are aiming for an acidic soil environment to maintain blue flowers, consider pairing the NANTUCKET BLUE with acid-loving woodland natives. Rhododendrons and azaleas, while requiring similar soil profiles, will bloom earlier in the season, providing sequential interest after the Hydrangea’s mid-summer performance. Ensure groundcover choices do not aggressively compete for the medium water supply required by the shrub.
Seasonal Care Calendar
Late Winter/Early Spring is the critical time for initial structural maintenance. Prune out any canes showing damage from winter cold, cutting them back to a healthy node or the base. This is also the optimal time to work in soil amendments, like lime or aluminum sulfate, if you wish to influence the upcoming summer’s flower color for your Bigleaf hydrangea.
Summer months focus primarily on consistent hydration and monitoring. Since Hydrangea macrophylla ‘Grenan’ NANTUCKET BLUE prefers medium water, deep, infrequent watering is generally better than light daily sprinkling, as this encourages deeper root growth. Mulching should be maintained around the root zone to keep the roots cool and reduce water evaporation from the soil surface.
In the Autumn, cease fertilizing to allow the plant to harden off for winter dormancy. Begin preparations for winter protection if you are situated in Zone 6, perhaps by applying a fresh layer of insulating mulch after the first hard frost, though pruning spent flowers is generally unnecessary as they can add winter interest.
