Reblooming Bigleaf Hydrangea – Unlock Continuous Blooms All Season

ByRimon Chowdhury Updated on

Ah, the majestic hydrangea! Few plants capture the heart of a gardener quite like it. Those lush, vibrant mopheads or delicate lacecaps bring an undeniable charm to any garden space. But let’s be honest, nothing’s more frustrating than lovingly tending your hydrangeas all season, only for them to produce a meager handful of flowers, or worse, none at all.

You’re not alone if you’ve faced this dilemma. Many gardeners adore bigleaf hydrangeas (Hydrangea macrophylla) but sometimes struggle with bloom consistency, especially after a harsh winter or an accidental snip at the wrong time. It can feel like a mystery, leaving you wondering if you’ll ever achieve that continuous cascade of color.

Well, wonder no more! We’re here to promise you that abundant, season-long flowers are absolutely within your reach, thanks to the magic of the reblooming bigleaf hydrangea. This comprehensive guide will reveal all the secrets to cultivating these garden superstars, ensuring your efforts are rewarded with a spectacular show from spring until frost.

In this article, you’ll discover how to choose the right cultivars, master essential care practices, learn the art of perfect pruning, understand soil pH for dazzling color, and protect your plants through winter. Get ready to transform your garden into a vibrant paradise!

Understanding Your Reblooming Bigleaf Hydrangea

Before we dive into the nitty-gritty of care, let’s get acquainted with what makes reblooming bigleaf hydrangeas so special. These aren’t your grandmother’s traditional hydrangeas, which typically bloom only on “old wood” – growth from the previous year.

Traditional bigleaf hydrangeas were often a gamble in colder climates. If a harsh winter killed back the old stems, or if you pruned them at the wrong time, you’d lose your flower buds for the entire season. It was heartbreaking!

What Makes Them Special? Old Wood vs. New Wood

The beauty of reblooming varieties lies in their unique ability to produce flowers on both old wood and new wood. This dual-blooming characteristic is a game-changer for gardeners.

It means that even if a severe winter zaps some of last year’s growth, or if you make a pruning mistake, your plant will still develop new flower buds on the current season’s growth. This ensures a much more reliable and extended blooming period.

Think of it as an insurance policy for your blooms. You get an initial flush of flowers from the old wood, often in early summer, followed by successive waves of blooms on the new wood throughout the summer and into fall. It’s truly a gift to the gardener!

Popular Reblooming Cultivars

The introduction of reblooming cultivars revolutionized the world of bigleaf hydrangeas. Here are some beloved series you might recognize and want to consider for your garden:

  • Endless Summer® Collection: This was the first widely available reblooming bigleaf hydrangea and remains incredibly popular. Varieties like ‘The Original’, ‘Blushing Bride’, ‘BloomStruck®’, and ‘Twist-n-Shout®’ (a lacecap variety) offer a fantastic range of colors and forms.
  • Let’s Dance® Series: Another excellent choice, offering compact sizes and vibrant colors. Look for ‘Rhythmic Blue®’, ‘Diva!®’, or ‘Can Do!®’ for reliable performance.
  • Everlasting® Series: Known for their sturdy stems and long-lasting blooms, these varieties also offer excellent reblooming capabilities.

When choosing a variety, always check its hardiness zone to ensure it’s suitable for your climate. Most rebloomers thrive in USDA Zones 4-9.

The Essentials for Abundant Blooms

While reblooming varieties are more forgiving, they still need the right foundation to truly flourish. Providing optimal growing conditions is the first step to a garden bursting with color.

Site Selection and Sunlight Needs

Bigleaf hydrangeas, including the reblooming types, generally prefer a spot with morning sun and afternoon shade. This is particularly true in warmer climates where intense afternoon sun can scorch their leaves and cause wilting.

In cooler climates (Zones 4-5), they might tolerate a bit more sun, but direct, scorching midday sun should still be avoided. Filtered light or dappled shade throughout the day can also work wonderfully.

A good rule of thumb is 4-6 hours of morning sun. Too much shade, however, can lead to fewer blooms and leggy growth, so it’s a balance!

Hydration is Key: Watering Best Practices

Hydrangeas, as their name suggests, are thirsty plants. Consistent moisture is crucial, especially during their active growing and blooming periods.

Newly planted hydrangeas need daily watering for the first few weeks, gradually tapering to 2-3 times a week for their first season. Established plants typically require deep watering once or twice a week, more frequently during hot, dry spells.

Feel the soil about an inch or two down. If it feels dry, it’s time to water. Avoid overhead watering late in the day, as this can encourage fungal diseases. Instead, water at the base of the plant using a soaker hose or drip irrigation.

Fueling the Flowers: Fertilization

A little boost of nutrition can go a long way in encouraging continuous blooming. However, don’t overdo it!

Apply a balanced, slow-release granular fertilizer in early spring as new growth emerges. Look for formulations specifically designed for hydrangeas or flowering shrubs, often with an N-P-K ratio like 10-10-10 or slightly higher in phosphorus (the middle number) to promote blooms, such as 15-30-15.

Avoid high-nitrogen fertilizers after spring, as too much nitrogen can promote leafy growth at the expense of flowers. Follow package directions carefully for application rates.

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Pruning Your Reblooming Bigleaf Hydrangea for Success

Pruning is often the most intimidating aspect of hydrangea care, but for reblooming varieties, it’s simpler than you might think. The key is understanding their unique bloom cycle.

When to Prune: The Golden Rule

For reblooming bigleaf hydrangeas, the general rule is to prune only as needed. Since they bloom on both old and new wood, aggressive pruning can reduce your initial flush of flowers.

The best time for any significant structural pruning is in late winter or early spring, just as new growth begins to emerge. At this time, you can easily identify dead, damaged, or weak stems.

Avoid pruning after mid-summer, as this could remove the new wood that would produce fall blooms, and even next year’s old wood buds.

Deadheading for More Flowers

This is where you actively encourage more blooms! Deadheading means removing spent flowers. It’s a simple, yet highly effective, task.

Once a flower fades and starts to brown, snip it off just above the first set of healthy leaves or buds below the spent bloom. This redirects the plant’s energy from seed production back into creating more flowers.

You can deadhead throughout the summer and early fall as blooms fade. This is one of the easiest ways to ensure your reblooming bigleaf hydrangea continues to put on a show.

Winter Pruning and Damage Control

In late winter or early spring, before significant new growth appears, inspect your plant. This is the time to remove:

  • Dead or damaged stems: Cut these back to the ground or to healthy wood. Look for stems that are brittle, discolored, or show no signs of life.
  • Weak or spindly growth: Remove any thin, unproductive stems to encourage stronger growth.
  • Crossing or rubbing branches: Trim one of the offending branches to prevent rubbing wounds that can invite disease.

Remember, less is often more with rebloomers. You’re cleaning up and shaping, not drastically cutting back the entire plant.

Mastering Soil pH for Vibrant Color

One of the most enchanting features of bigleaf hydrangeas is their ability to change flower color based on soil pH. Reblooming varieties are no exception!

The Blue vs. Pink Mystery

The color transformation is all about aluminum availability in the soil:

  • Acidic soil (pH 5.5 and below): Aluminum is readily available, resulting in blue flowers.
  • Alkaline soil (pH 6.5 and above): Aluminum is bound up and unavailable, leading to pink flowers.
  • Neutral soil (pH 5.5-6.5): You’ll often see a mix of purple or muddy colors, or even different shades on the same plant.

White varieties, like ‘Blushing Bride’, are bred to remain white regardless of soil pH. Some cultivars are also more resistant to color change than others, so always check the plant tag!

Testing Your Soil

The first step to manipulating color is knowing your current soil pH. You can purchase an inexpensive soil test kit from any garden center, or send a sample to your local agricultural extension office for a more detailed analysis.

This test will give you a baseline and inform your next steps. Don’t guess – testing is crucial for success!

Adjusting pH: Aluminum Sulfate and Garden Lime

Once you know your pH, you can make adjustments:

  1. For Blue Flowers (Lower pH):
    • Add aluminum sulfate to the soil. This acidifies the soil and provides the necessary aluminum.
    • Alternatively, use elemental sulfur or sphagnum peat moss.
    • Start treatments in early spring, and apply according to package directions. It often takes several applications over time to see a significant change.
  2. For Pink Flowers (Raise pH):
    • Add garden lime (dolomitic or calcitic) to the soil. This makes the soil more alkaline.
    • Another option is wood ash, but use sparingly.
    • Apply in fall or early spring, following package instructions.

Consistency is key, and it’s a gradual process. Don’t expect instant results; soil pH changes take time. Always wear gloves and follow safety instructions when handling soil amendments.

Protecting Your Investment: Winter Care

Even though reblooming hydrangeas bloom on new wood, protecting their old wood and root system through winter is still vital for the earliest and most abundant flush of blooms.

Preparing for Frost

In colder zones (USDA Zones 4-6), a little winter protection can make a huge difference, especially for the flower buds that form on old wood.

  • Mulch heavily: Once the ground begins to freeze, apply a thick layer (4-6 inches) of organic mulch around the base of the plant. Materials like shredded leaves, straw, or pine needles will insulate the roots and lower stems.
  • Protect above-ground stems: In very cold or exposed areas, you can create a cage of chicken wire around the plant and fill it with leaves or straw. This insulates the stems and buds. You can also wrap the plant in burlap.

Remove any heavy coverings in early spring once the danger of hard frost has passed, allowing new growth to emerge.

Container Hydrangeas in Winter

If you’re growing a reblooming bigleaf hydrangea in a pot, winter care is even more critical, as container plants are more susceptible to freezing temperatures.

  • Bring indoors: In colder zones, the best option is to bring the potted hydrangea into an unheated garage, shed, or basement once temperatures consistently drop below freezing.
  • Keep dormant: While indoors, the plant needs very little water—just enough to keep the soil from completely drying out. Do not fertilize.
  • Gradual reintroduction: In spring, gradually reintroduce the plant to outdoor conditions after the last frost, starting with a shaded spot before moving to its permanent location.
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Even in milder climates, consider moving container plants to a sheltered spot against a house or wall to protect them from harsh winds and freezing temperatures.

Troubleshooting Common Issues

Even with the best care, sometimes things go awry. Here are a few common issues and how to tackle them.

Why Aren’t My Hydrangeas Blooming?

This is the most frequent question gardeners ask. For a reblooming bigleaf hydrangea, several factors could be at play:

  • Improper Pruning: Pruning too late in the season can remove both old and new wood buds. Remember, prune only what’s necessary in late winter/early spring, and deadhead spent blooms.
  • Lack of Sunlight: Too much shade can result in lush foliage but few flowers. Ensure your plant gets at least 4-6 hours of morning sun.
  • Winter Damage: Even rebloomers can suffer if a severe winter zaps too much old wood, or if new growth emerges too early and is hit by a late frost. This is where good winter protection pays off.
  • Nutrient Imbalance: Too much nitrogen (the first number in the N-P-K ratio) can encourage leafy growth at the expense of blooms. Use a balanced or phosphorus-rich fertilizer.
  • Immature Plant: Very young plants sometimes need a year or two to establish a strong root system before they put on a spectacular floral display. Be patient!

Carefully review your care routine and the plant’s environment to pinpoint the cause.

Pests and Diseases to Watch For

Hydrangeas are generally robust, but they can occasionally encounter issues:

  • Aphids: Small, soft-bodied insects that cluster on new growth. A strong spray of water or insecticidal soap usually takes care of them.
  • Spider Mites: Tiny pests that thrive in hot, dry conditions, causing stippling on leaves and fine webbing. Increase humidity and use insecticidal soap.
  • Powdery Mildew: A white, powdery coating on leaves, often due to poor air circulation. Ensure good spacing between plants and avoid overhead watering. Fungicidal sprays can help in severe cases.
  • Leaf Spot: Various fungal spots can appear on leaves. Remove affected leaves and ensure good air circulation.

Maintaining good plant health through proper watering, feeding, and air circulation is your best defense against most pests and diseases.

Frequently Asked Questions About Reblooming Bigleaf Hydrangea

We’ve covered a lot, but here are some quick answers to common queries.

Do reblooming hydrangeas need more fertilizer?

Not necessarily more fertilizer, but consistent, appropriate fertilization is beneficial. A balanced, slow-release granular fertilizer in early spring is usually sufficient. Avoid over-fertilizing, especially with high-nitrogen formulas, as this can lead to lush leaves but fewer flowers.

Can I grow reblooming bigleaf hydrangeas in pots?

Absolutely! They are excellent candidates for container gardening, especially compact varieties. Just ensure the pot is large enough (at least 18-24 inches in diameter for mature plants), has good drainage, and remember that container plants need more frequent watering and winter protection than those in the ground.

What’s the difference between reblooming and non-reblooming hydrangeas?

The main difference is their ability to bloom on “new wood” (current season’s growth) in addition to “old wood” (previous season’s growth). Non-reblooming varieties only bloom on old wood, making them more vulnerable to winter damage or improper pruning that can eliminate an entire year’s worth of flowers.

How long do the blooms last?

Individual blooms can last for weeks, often slowly changing color as they age. Because reblooming varieties produce successive flushes of flowers, you can enjoy continuous blooms from early summer until the first hard frost, offering a much longer season of interest than traditional types.

When should I plant them?

The best times to plant reblooming bigleaf hydrangeas are in spring after the danger of frost has passed, or in early fall, giving them ample time to establish their root systems before winter. Avoid planting in the heat of summer, as this can stress the plant.

Go Forth and Grow!

There you have it! The secrets to cultivating a stunning display from your reblooming bigleaf hydrangea are now at your fingertips. These remarkable plants truly offer the best of both worlds: the classic beauty of bigleaf hydrangeas with the added assurance of season-long blooms.

Remember, gardening is an art and a science, and every plant is a journey. Pay attention to your hydrangeas, observe how they respond to your care, and don’t be afraid to make small adjustments. With the right knowledge and a little bit of patience, you’ll be enjoying a breathtaking show of color from your garden all season long. Happy gardening!

Rimon Chowdhury
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