Hydrangea Arborescens Vs Macrophylla – Choosing The Perfect Bloom

ByRimon Chowdhury Updated on

Ever walked into a nursery, overwhelmed by the sheer variety of hydrangeas, and wondered which one is truly right for your garden? You’re not alone! Many gardeners, myself included, have faced the delightful dilemma of choosing between these stunning shrubs. Two of the most popular types you’ll encounter are Hydrangea arborescens, often known as smooth hydrangeas, and Hydrangea macrophylla, or bigleaf hydrangeas.

While both offer breathtaking blooms, they have distinct personalities and care requirements that make them suited for different garden styles and climates. Understanding the nuances between hydrangea arborescens vs macrophylla is key to cultivating a thriving, floriferous display.

In this comprehensive guide, we’ll dive deep into the world of these magnificent plants. We’ll explore their unique characteristics, growth habits, pruning needs, and best uses, helping you confidently select the perfect hydrangea for your outdoor space. Get ready to unlock the secrets to a garden bursting with beautiful hydrangea blooms!

Getting to Know Our Stars: Hydrangea Arborescens (Smooth Hydrangea)

Let’s start with the delightful Hydrangea arborescens, often lovingly called the smooth hydrangea. These beauties are native to North America, making them incredibly adaptable and resilient in many climates. They’re a fantastic choice for gardeners seeking reliable, show-stopping blooms.

Signature Blooms and Foliage

Smooth hydrangeas are best known for their large, rounded flower clusters, typically in shades of white or greenish-white. Think of classic varieties like ‘Annabelle’ with its enormous, sometimes floppy, white globes, or ‘Incrediball’ which boasts stronger stems to support its massive blooms.

More recently, pink-flowering varieties like ‘Invincibelle Spirit’ have emerged, offering even more color options. The foliage is generally a vibrant green, providing a lush backdrop to the spectacular flowers. Their blooms typically appear in early summer and can last well into the fall, offering a long season of interest.

Growth Habits and Hardiness

These hydrangeas are deciduous shrubs, meaning they lose their leaves in winter. They grow relatively quickly, forming a rounded, mounded shape, usually reaching heights and widths of 3 to 5 feet, though some can get larger. Hydrangea arborescens is incredibly cold-hardy, thriving in USDA Zones 3 to 9.

What makes them so dependable is their ability to flower on new wood. This means that even if a harsh winter kills the stems back to the ground, new growth will emerge in spring and still produce flowers that same year. This characteristic makes them wonderfully forgiving, especially for beginners or those in colder regions.

Pruning for Success

Pruning a smooth hydrangea is straightforward and largely depends on your desired size and shape. Since they bloom on new wood, you can prune them quite aggressively without sacrificing the next season’s flowers.

  • Late Winter/Early Spring: This is the ideal time to prune. You can cut the entire plant back by about one-third, or even down to 6-12 inches from the ground, to encourage strong new growth and larger blooms.
  • Deadheading: While not strictly necessary for future blooms, removing spent flowers (deadheading) can tidy up the plant and may encourage a slight rebloom in some varieties.
  • Addressing Floppy Stems: If your ‘Annabelle’ hydrangeas tend to flop under the weight of their blooms after rain, consider leaving some older, stronger stems for support, or opt for varieties like ‘Incrediball’ bred for sturdier stems.

Meet the Bigleaf Beauty: Hydrangea Macrophylla (Bigleaf Hydrangea)

Now, let’s turn our attention to the beloved Hydrangea macrophylla, affectionately known as the bigleaf hydrangea. These are perhaps the most iconic hydrangeas, famous for their ability to change flower color based on soil pH. They bring a touch of classic charm to any garden space.

Iconic Flowers and Color Changes

Bigleaf hydrangeas are celebrated for their vibrant, often massive, flower clusters. You’ll typically find two main flower forms:

  • Mophead: These have large, rounded, ball-like flower heads, densely packed with sterile florets. They are the quintessential “hydrangea flower.”
  • Lacecap: These feature a flatter flower head with a central cluster of tiny, fertile flowers surrounded by a ring of larger, showy sterile florets. They offer a more delicate appearance.

The magic of Hydrangea macrophylla lies in its color-changing ability. Mophead and lacecap varieties can bloom in shades of blue, pink, purple, or even white. The color, for most varieties, is determined by the soil’s pH:

  • Acidic Soil (pH below 6.0): Encourages blue flowers.
  • Alkaline Soil (pH above 7.0): Promotes pink flowers.
  • Neutral Soil (pH 6.0-7.0): Often results in purple or mixed pink and blue blooms.

White varieties, like ‘Madame Emile Mouillère’, typically remain white regardless of soil pH. Changing flower color is a fun experiment for many gardeners, involving soil amendments like aluminum sulfate for blue or garden lime for pink.

Understanding Growth and Hardiness

Like smooth hydrangeas, bigleaf hydrangeas are deciduous shrubs. They typically grow to a similar size, ranging from 3 to 6 feet tall and wide, depending on the cultivar. Their hardiness varies a bit more than arborescens, generally thriving in USDA Zones 5 to 9.

The key difference in growth for many traditional macrophylla varieties is that they bloom on old wood—meaning the flower buds for the next season are formed on the previous year’s growth. This makes them more susceptible to winter damage or late spring frosts, which can kill those precious flower buds, leading to a year without blooms.

However, modern breeding has given us “reblooming” or “everblooming” varieties, such as those in the ‘Endless Summer’ series. These cultivars bloom on both old and new wood, offering a much higher chance of consistent flowering, even after a tough winter or incorrect pruning. This innovation has made bigleaf hydrangeas much more reliable for gardeners in marginal zones.

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The Art of Pruning Bigleaf Hydrangeas

Pruning Hydrangea macrophylla, especially old-wood bloomers, requires a bit more finesse to ensure you don’t accidentally cut off the next season’s flowers.

  • After Flowering (Late Summer): For old-wood bloomers, prune immediately after the flowers fade in late summer. This allows the plant enough time to form new buds for the following year. Remove only dead, damaged, or weak stems, and shape as needed.
  • Late Winter/Early Spring: For reblooming varieties (new and old wood bloomers), you can prune in late winter or early spring, as they will still produce flowers on new growth. Focus on removing dead or weak stems.
  • Deadheading: Removing spent flowers can improve the plant’s appearance and may encourage more blooms on reblooming types.
  • Avoid Heavy Pruning: For traditional old-wood bloomers, avoid cutting back significantly in late fall, winter, or early spring, as this will remove flower buds.

Hydrangea Arborescens vs Macrophylla: A Head-to-Head Comparison

Now that we’ve met each player, let’s put them side-by-side. Understanding these distinctions is crucial for making the best choice for your garden. The comparison between hydrangea arborescens vs macrophylla highlights their unique strengths.

Bloom Characteristics: Size, Shape, and Color

  • Hydrangea Arborescens: Typically large, rounded clusters (mophead-like) of white or greenish-white flowers, with some pink varieties available. Flower color is generally stable and not influenced by soil pH.
  • Hydrangea Macrophylla: Features both mophead (rounded) and lacecap (flat-topped) flower forms. Colors range from pink, blue, purple, and white, with the blues and pinks being pH-dependent. White varieties remain white.

Growth & Maintenance: What to Expect

  • Hydrangea Arborescens:
    • Blooms on: New wood.
    • Pruning: Very forgiving; can be cut back hard in late winter/early spring without losing blooms.
    • Hardiness: Very cold-hardy (USDA Zones 3-9).
    • Ease of Care: Generally low-maintenance, excellent for beginners.
  • Hydrangea Macrophylla:
    • Blooms on: Traditionally old wood, but reblooming varieties bloom on both old and new wood.
    • Pruning: Requires careful timing for old-wood bloomers (after flowering). Rebloomers are more forgiving.
    • Hardiness: Less cold-hardy than arborescens (USDA Zones 5-9); old-wood buds can be susceptible to winter kill.
    • Ease of Care: Can be more challenging for beginners, especially old-wood types, due to pruning needs and winter protection. Rebloomers simplify things considerably.

Ideal Growing Conditions

  • Hydrangea Arborescens:
    • Sunlight: Tolerates more sun than macrophylla, especially in northern climates. Partial shade is ideal, but full sun (6+ hours) is often fine with consistent moisture.
    • Soil: Prefers rich, well-draining soil with consistent moisture. Tolerant of a range of soil types.
  • Hydrangea Macrophylla:
    • Sunlight: Prefers morning sun and afternoon shade, especially in hotter climates. Too much direct, intense sun can scorch leaves and flowers.
    • Soil: Requires consistently moist, well-draining soil rich in organic matter. Soil pH is critical for flower color.

Planting and Care: Ensuring Your Hydrangeas Thrive

No matter which hydrangea you choose, proper planting and ongoing care are essential for a robust and floriferous plant. Think of these as foundational steps for gardening success.

Site Selection and Soil Preparation

Choosing the right spot is paramount. Observe your garden throughout the day to understand its light patterns. For both types, good air circulation is important to prevent fungal diseases.

  • Sunlight: As discussed, arborescens can handle more sun, while macrophylla appreciates afternoon shade.
  • Soil pH: If you’re set on a specific color for your macrophylla, test your soil pH before planting. Kits are readily available at garden centers.
  • Drainage: Hydrangeas hate “wet feet.” Amend heavy clay soils with compost or other organic matter to improve drainage. For sandy soils, compost will help retain moisture.
  • Planting Hole: Dig a hole twice as wide as the root ball and just as deep. Loosen any circling roots before placing the plant. Backfill with native soil mixed with a bit of compost.

Watering Wisdom

Hydrangeas are notoriously thirsty plants, especially during their establishment phase and hot, dry periods. Consistent moisture is key to large, healthy blooms.

  • New Plants: Water deeply 2-3 times a week during the first year, or more frequently during heatwaves.
  • Established Plants: Aim for about 1 inch of water per week, either from rain or irrigation. Check the soil moisture regularly by sticking your finger about 2 inches deep. If it feels dry, it’s time to water.
  • Mulching: Apply a 2-3 inch layer of organic mulch (like shredded bark or compost) around the base of your hydrangeas. This helps retain soil moisture, regulate soil temperature, and suppress weeds. Keep mulch a few inches away from the main stem.

Fertilization for Robust Growth

A balanced fertilizer can boost your hydrangea’s performance, but avoid over-fertilizing, which can promote leafy growth at the expense of flowers.

  • Timing: Fertilize in early spring as new growth emerges. You can do a second, lighter feeding in early summer.
  • Type: Use a slow-release granular fertilizer formulated for flowering shrubs, or a balanced granular fertilizer (e.g., 10-10-10 or 12-4-8). For macrophylla, if you’re trying to adjust color, use specific fertilizers for acid-loving plants (for blue) or those higher in phosphorus (for pink).
  • Application: Always follow package directions. Scatter the fertilizer around the drip line of the plant (where the leaves extend) and water it in thoroughly.

Pest and Disease Management

Both types of hydrangeas are generally robust, but they can occasionally encounter common garden pests or diseases. Don’t worry—these are usually manageable!

  • Pests: Aphids, spider mites, and slugs are the most common culprits. A strong spray of water can dislodge aphids. For spider mites, increase humidity and consider insecticidal soap. Slugs can be managed with traps or organic baits.
  • Diseases: Powdery mildew can occur in humid conditions or areas with poor air circulation. Ensure proper spacing and prune for airflow. Fungal leaf spot can also appear, but usually isn’t severe enough to warrant chemical treatment. Always remove and discard infected leaves.
  • Prevention is Key: Good cultural practices—proper watering, spacing, and air circulation—are your best defense against most problems.
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Choosing the Right Hydrangea for Your Garden Style

Now for the fun part: deciding which hydrangea fits your aesthetic and lifestyle. Both smooth and bigleaf hydrangeas offer incredible beauty, but their characteristics lend them to different roles in the landscape.

Low-Maintenance Landscapes

If you’re a busy gardener, new to hydrangeas, or just prefer a more hands-off approach, Hydrangea arborescens is your champion. Its ability to bloom on new wood means you don’t have to fret over pruning timing, and its cold hardiness makes it a reliable performer even after harsh winters.

Varieties like ‘Incrediball’ are excellent for sturdy, large white blooms, while ‘Invincibelle Wee White’ offers a compact, pink option for smaller spaces. Don’t worry—these flowers are perfect for beginners!

Vibrant Borders and Mass Plantings

For creating a dramatic, colorful border or mass planting, both types shine. Hydrangea macrophylla, especially the reblooming varieties, provides a continuous show of pinks, blues, and purples that can be truly breathtaking. Imagine a hedge of ‘Endless Summer’ hydrangeas providing season-long color!

If you love the classic white, billowy look, a mass planting of ‘Annabelle’ hydrangeas creates an unparalleled ethereal effect. Consider pairing them with contrasting foliage plants or other summer bloomers for a truly dynamic display.

Container Gardening and Small Spaces

For patios, balconies, or smaller garden plots, compact varieties are key. Both types now offer excellent options for containers.

  • Hydrangea Arborescens: Look for dwarf varieties like ‘Invincibelle Wee White’ which stays under 3 feet tall and wide, perfect for a decorative pot.
  • Hydrangea Macrophylla: Many reblooming series now include compact cultivars, such as ‘Little Endless Summer’ or ‘Pistachio’, that are well-suited for container life. Just remember container plants dry out faster and may need more frequent watering.

Frequently Asked Questions About Hydrangea Arborescens vs Macrophylla

Let’s address some common questions that pop up when gardeners are deciding between these two popular hydrangea types.

Can I grow both types in the same garden?

Absolutely! Many gardeners successfully grow both Hydrangea arborescens and Hydrangea macrophylla in their landscapes. Just ensure you place them in locations that meet their individual sunlight and soil preferences. For instance, put the arborescens in a spot with more sun, and the macrophylla in an area that gets morning sun and afternoon shade.

Which one is better for beginners?

For beginners, Hydrangea arborescens is generally more forgiving. Its ability to bloom on new wood means that even if you prune it incorrectly or a harsh winter hits, you’re still likely to get flowers. They are also incredibly cold-hardy and less prone to “no bloom” frustrations.

How do I change the color of my Hydrangea macrophylla?

To encourage blue blooms, you’ll need acidic soil (pH below 6.0). You can achieve this by applying aluminum sulfate or a soil acidifier in early spring. For pink blooms, aim for alkaline soil (pH above 7.0) by adding garden lime. Start these amendments in early spring, and remember that it can take time and consistent application to see significant color changes.

What’s the biggest mistake gardeners make with these hydrangeas?

The biggest mistake is often incorrect pruning, particularly with old-wood blooming Hydrangea macrophylla. Pruning at the wrong time (e.g., in late fall or early spring) can remove the flower buds that formed on last year’s stems, resulting in no blooms. For arborescens, the common issue is sometimes floppy stems, especially with older ‘Annabelle’ varieties, which can be mitigated by choosing stronger-stemmed cultivars or providing support.

Conclusion

Choosing between Hydrangea arborescens and Hydrangea macrophylla doesn’t have to be a daunting task. Both are truly magnificent plants, each bringing its own unique charm and set of care requirements to the garden. By understanding their distinct characteristics—from how they bloom to their preferred growing conditions—you’re now equipped to make an informed decision that perfectly suits your garden’s needs and your personal gardening style.

Whether you opt for the robust, easy-care smooth hydrangea or the classic, color-changing bigleaf variety (perhaps a reblooming one for less fuss!), you’re investing in seasons of glorious blooms. Don’t be afraid to experiment, observe your plants, and enjoy the process. Your garden is a canvas, and these hydrangeas are ready to paint it with breathtaking beauty. Go forth and grow!

Rimon Chowdhury
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