Hydrangea

Hydrangeas, also commonly known as Hortensia, and bearing the botanical name Hydrangea, are beloved flowering shrubs adored for their large, showy blooms and diverse color palette. These captivating plants, with their mophead, lacecap, and panicle varieties, offer a range of aesthetic options for any garden. At Gardencenterpoint.com, we understand the allure of these beautiful plants and provide resources to help you succeed in cultivating them.

Whether you’re looking to buy hydrangea plants, understand hydrangea care, or find a local nursery specializing in these beauties, we’ve got you covered. Our comprehensive guide offers solutions for all your Hydrangea, or Hortensia, needs.

Understanding Hydrangea Varieties: A World of Choice

One of the most captivating aspects of hydrangeas is the sheer variety available. Choosing the right type for your garden’s conditions and your aesthetic preferences is crucial for success.

Common Names	Hydrangea, Hortensia
Botanical Name	Hydrangea spp.
Family	Hydrangeaceae
Genus	Hydrangea
Species	macrophylla, paniculata, arborescens, quercifolia, serrata (and others)
Origin	Primarily Asia (Japan, China, Korea) and North America
Life Cycle	Perennial (woody shrub)
Plant Type	Deciduous Shrub (some H. serrata cultivars are semi-evergreen)
Hardiness Zones	H. macrophylla (6-9), H. paniculata (3-8), H. arborescens (3-9), H. quercifolia (5-9), H. serrata (6-9). Newer cultivars may have expanded ranges.
Sunlight	Generally prefers morning sun and afternoon shade. H. paniculata is most sun-tolerant. H. arborescens tolerates more shade.
Maintenance	Generally low to moderate. Pruning requirements vary significantly by species.
Water	Moderate to high. Requires consistent moisture, especially during establishment and hot weather. Avoid overwatering.
Drainage	Well-Drained. Hydrangeas do not tolerate waterlogged soil.
Spacing	Varies by species and cultivar mature size. Typically 3-10 feet.
Flowering Period	Generally summer. Some reblooming H. macrophylla cultivars extend the bloom season. H. paniculata often blooms into fall.
Height	From 1 foot (dwarf varieties) to 15 feet (some H. paniculata).
Growth Rate	Moderate to fast, depending on species and conditions.
Flower Color	Varies by species and soil pH (H. macrophylla and H. serrata): Blue, pink, purple, white, green, red.
Stem Color	Green, brown, reddish-brown (depending on age and species). H. quercifolia has exfoliating bark.
Flower Benefit	Showy, long-lasting blooms. Attracts pollinators (fertile florets).
Garden Style	Cottage, formal, modern, woodland, Japanese.
Uses	Foundation plantings, mixed borders, woodland gardens, container gardens, hedges, cut flowers, dried flowers.
Soil pH Preference	Acidic (pH < 6.0) for blue flowers, Alkaline (pH > 7.0) for pink flowers.
Propagation	Stem cuttings, layering, division (depending on species).
Deer Resistance	Low to moderate. Deer may browse, especially if other food is scarce.
Toxicity	Contain cyanogenic glycosides; low to moderate toxicity if ingested.

Hydrangea macrophylla (Bigleaf Hydrangea):

This is arguably the most popular type, known for its large, showy blooms. It includes two main groups:

• Mophead Hydrangeas: These have large, round flower heads composed almost entirely of sterile florets. These are the classic “snowball” hydrangeas. Examples: ‘Nikko Blue’ ‘Endless Summer’ ‘Penny Mac’
• Lacecap Hydrangeas: These have flattened flower heads with a center of small, fertile florets surrounded by a ring of larger, sterile florets. They offer a more delicate, natural look. Examples: ‘Blue Wave’ ‘Twist-n-Shout’
• Key Characteristics:
  • Flower Color: The color of Hydrangea macrophylla blooms is famously influenced by soil pH. Acidic soil (pH below 6.0) produces blue flowers, while alkaline soil (pH above 7.0) results in pink flowers. Neutral soil may produce a mix of pink, blue, and purple shades.
  • Bloom Time: Typically blooms in summer, with some reblooming varieties extending the season.
  • Hardiness Zones: Generally hardy in USDA zones 6-9, although some newer cultivars have expanded this range.
  • Pruning: Most Hydrangea macrophylla varieties bloom on old wood (growth from the previous season). Pruning should be done immediately after flowering, only to remove dead or weak stems.

Hydrangea paniculata (Panicle Hydrangea):

These hydrangeas are known for their cone-shaped flower clusters (panicles). They are generally more cold-hardy and sun-tolerant than H. macrophylla.

• Key Characteristics:
  • Flower Color: Typically start white or cream and may age to pink or red. Soil pH does not affect flower color.
  • Bloom Time: Blooms in summer, often extending into fall.
  • Hardiness Zones: Generally hardy in USDA zones 3-8, making them a good choice for colder climates.
  • Pruning: Blooms on new wood (growth from the current season). Can be pruned in late winter or early spring. Examples: ‘Limelight’ ‘Pinky Winky’ ‘Quick Fire’

Hydrangea arborescens (Smooth Hydrangea):

This North American native is known for its large, rounded flower heads and tolerance of shade.

• Key Characteristics:
  • Flower Color: Typically white, although some cultivars have pink blooms. Soil pH does not affect flower color.
  • Bloom Time: Blooms in summer.
  • Hardiness Zones: Generally hardy in USDA zones 3-9.
  • Pruning: Blooms on new wood. Can be pruned back hard in late winter or early spring. Examples: ‘Annabelle’ ‘Incrediball’

Hydrangea quercifolia (Oakleaf Hydrangea):

This species is prized for its distinctive oak-shaped leaves, which turn beautiful shades of red, orange, and purple in the fall.

• Key Characteristics:
  • Flower Color: White, aging to pink. Soil pH does not affect flower color.
  • Bloom Time: Blooms in summer.
  • Hardiness Zones: Generally hardy in USDA zones 5-9.
  • Pruning: Blooms on old wood. Prune lightly after flowering to remove dead or weak stems. Examples: ‘Snow Queen’ ‘Alice’

Hydrangea serrata (Mountain Hydrangea):

Similar to H. macrophylla, but generally more compact and with smaller, lacecap-type flowers.

• Key Characteristics:
  • Flower Color: Flower color is influenced by soil pH, similar to H. macrophylla.
  • Bloom Time: Blooms in summer.
  • Hardiness Zones: Generally hardy in USDA zones 6-9.
  • Pruning: Blooms on old wood. Prune lightly after flowering. *Examples: ‘Bluebird’ ‘Tuff Stuff’

Planting Hydrangeas: Setting the Stage for Success

Proper planting is essential for establishing healthy, vigorous hydrangeas. Here’s a step-by-step guide:

1. Choosing the Right Location:
   • Sunlight: Most hydrangeas prefer morning sun and afternoon shade, especially in hotter climates. H. paniculata is the most sun-tolerant. H. arborescens can tolerate more shade.
   • Soil: Hydrangeas prefer well-drained, fertile soil rich in organic matter. Avoid heavy clay soils that retain too much water.
   • Spacing: Space plants according to their mature size, allowing for good air circulation.
2. Timing:
   • The best time to plant hydrangeas is in the spring or fall, when temperatures are moderate.
3. Planting Process:
   • Dig a hole twice as wide as the root ball and just as deep.
   • Amend the soil with compost or other organic matter to improve drainage and fertility.
   • Gently remove the plant from its container and loosen any circling roots.
   • Place the plant in the hole so that the top of the root ball is level with the ground.
   • Backfill the hole with the amended soil, tamping it down gently.
   • Water thoroughly.
   • Add a layer of mulch around the base of the plant to conserve moisture and suppress weeds.

Hydrangea Care: Nurturing Your Blooms

Consistent care is key to keeping your hydrangeas healthy and producing abundant blooms.

Watering:

• Hydrangeas need consistent moisture, especially during hot, dry periods.
• Water deeply and regularly, especially during the first year after planting.
• Avoid overhead watering, which can promote fungal diseases.
• Mulching helps retain soil moisture.
• The amount of water will depend on several factors:
  1. Rainfall
  2. Type of Soil
  3. Climate
  4. Hydrangea Variety

Fertilizing:

• Hydrangeas benefit from regular fertilization, but over-fertilizing can lead to excessive foliage growth and fewer blooms.
• Use a balanced, slow-release fertilizer formulated for flowering shrubs.
• Apply fertilizer in early spring, just as new growth emerges.
• For H. macrophylla, you can use a fertilizer specifically formulated to enhance blue or pink blooms, depending on your desired color.
• A soil test can help determine the specific nutrient needs of your soil.

Pruning:

• Pruning techniques vary depending on the hydrangea species.
  • H. macrophylla and H. quercifolia: Prune immediately after flowering, only removing dead or weak stems. These species bloom on old wood.
  • H. paniculata and H. arborescens: Prune in late winter or early spring. These species bloom on new wood.
• Deadheading (removing spent flowers) can encourage reblooming in some varieties.

Winter Protection:

• In colder climates, some hydrangeas, particularly H. macrophylla, may need winter protection to protect their flower buds from freezing temperatures.
• Wrap the plants with burlap or cover them with a thick layer of leaves or straw after the first hard frost.
• Remove the protection in early spring, after the danger of frost has passed.

Changing Hydrangea Color: The pH Factor

One of the most fascinating aspects of Hydrangea macrophylla and Hydrangea serrata is their ability to change flower color depending on soil pH. This is due to the presence of anthocyanin pigments, which are affected by the availability of aluminum in the soil.

• Acidic Soil (pH below 6.0): Aluminum is more readily available in acidic soil, leading to blue flowers. To acidify the soil, you can use:
  • Aluminum sulfate
  • Soil acidifiers
  • Coffee grounds (use sparingly)
  • Pine needles
• Alkaline Soil (pH above 7.0): Aluminum is less available in alkaline soil, leading to pink flowers. To make the soil more alkaline, you can use:
  • Dolomitic lime
  • Wood ashes (use sparingly)
• Neutral Soil (pH 6.0-7.0): May produce a mix of pink, blue, and purple shades.

Important Note: It’s easier to change the color of pink hydrangeas to blue than vice versa. Changing the soil pH takes time, so be patient. It may take several months or even a year to see the full effect of your efforts. A soil test is highly recommended before attempting to change the soil pH.

Common Hydrangea Problems and Solutions

Hydrangeas are generally robust plants, but they can be susceptible to certain pests and diseases.

Pests:

• Aphids: Small, sap-sucking insects that can cause distorted growth and honeydew buildup.
  • Control: Insecticidal soap, neem oil, or introduce beneficial insects like ladybugs.
• Spider Mites: Tiny pests that thrive in hot, dry conditions and cause stippling and yellowing of leaves.
  • Control: Insecticidal soap, neem oil, or horticultural oil.
• Japanese Beetles: Can skeletonize leaves.
  • Control: Handpicking, traps, or insecticides.
• Slugs and Snails: Can chew holes in leaves.
  • Control: Handpicking, beer traps, or diatomaceous earth.

Diseases:

• Powdery Mildew: A fungal disease that causes a white, powdery coating on leaves.
  • Control: Improve air circulation, avoid overhead watering, and use fungicides.
• Leaf Spot: Fungal diseases that cause brown or black spots on leaves.
  • Control: Remove and destroy infected leaves, improve air circulation, and use fungicides.
• Botrytis Blight: A fungal disease that causes brown, mushy spots on flowers and leaves.
  • Control: Remove and destroy infected plant parts, improve air circulation, and use fungicides.
• Root Rot: Caused by overwatering or poorly drained soil.
  • Control: Improve drainage, avoid overwatering, and use fungicides.

Propagating Hydrangeas: Creating New Plants

Hydrangeas can be propagated through several methods:

Stem Cuttings:

• This is the most common method.
• Take cuttings in spring or early summer from non-flowering shoots.
• Cuttings should be 4-6 inches long and have several sets of leaves.
• Remove the lower leaves and dip the cut end in rooting hormone.
• Insert the cuttings into a moist potting mix.
• Keep the cuttings humid and warm until they root.

Layering:

• This method involves bending a low-growing stem to the ground and burying a portion of it.
• The buried portion will develop roots, and the new plant can then be separated from the parent plant.

Division:

• This method is best for H. arborescens and H. paniculata.
• Divide the plant in early spring or fall.
• Dig up the plant and carefully separate the root ball into smaller sections.
• Replant the divisions immediately.

Hydrangeas in the Landscape: Design Ideas

Hydrangeas are versatile plants that can be used in a variety of landscape settings:

• Foundation Plantings: Hydrangeas can soften the lines of a house and add curb appeal.
• Mixed Borders: Combine hydrangeas with other shrubs, perennials, and annuals for a colorful display.
• Woodland Gardens: H. arborescens and H. quercifolia are well-suited for shady, woodland settings.
• Container Gardens: Smaller hydrangea varieties can be grown in containers on patios or decks.
• Hedges: Some hydrangea varieties can be used to create informal hedges.
• Cut Flowers: Hydrangea blooms make beautiful cut flowers, both fresh and dried.

Hydrangeas and Scientific Research

Hydrangeas have been the subject of numerous scientific studies, focusing on various aspects of their biology, cultivation, and potential uses. Here are a few examples:

• Soil pH and Flower Color: Research has extensively documented the relationship between soil pH and flower color in H. macrophylla. Studies have identified the specific anthocyanin pigments involved and the role of aluminum in the color-changing process. (Source: Journal of the American Society for Horticultural Science)
• Cold Hardiness: Researchers are continuously working to develop new hydrangea cultivars with improved cold hardiness, expanding the range where these plants can be grown. (Source: HortScience)
• Medicinal Properties: Some studies have investigated the potential medicinal properties of hydrangea extracts, particularly their antioxidant and anti-inflammatory effects. (Source: Journal of Ethnopharmacology) This is a developing field and requires more research.
• Phytoremediation: Studies have examined the ability that Hydrangeas will absorb heavy metals. Some are good and some are not.(Source: Department of Environmental Science, Policy, and Management, University of California, Berkeley)

Finding Hydrangeas: Where to Buy and Learn More

Gardencenterpoint.com is dedicated to providing gardeners with the resources they need to succeed. While we are not a retailer, we can guide you to the best places to find healthy hydrangea plants and expert advice:

• Local Nurseries: Visiting local nurseries allows you to see the plants in person, ask questions, and get region-specific advice. Many nurseries specialize in hydrangeas and offer a wide selection of varieties.
• Botanical Gardens: Botanical gardens are excellent places to see mature hydrangea specimens and learn about different species and cultivars.
• Online Retailers: While we don’t endorse specific retailers, many reputable online nurseries offer a wide selection of hydrangeas. Be sure to read reviews and check their shipping policies before ordering.
• University Extension Services: Your local university extension service is a valuable resource for gardening information, including advice on growing hydrangeas in your area.

Frequently Asked Questions (FAQ) About Hydrangeas

• Q: Why aren’t my hydrangeas blooming?
  • A: There are several possible reasons:
    • Incorrect pruning: Pruning at the wrong time of year can remove flower buds.
    • Insufficient sunlight: Most hydrangeas need at least 4 hours of sunlight per day.
    • Over-fertilizing: Too much nitrogen can promote foliage growth at the expense of flowers.
    • Winter damage: Cold temperatures can damage flower buds.
    • Young plant: It may take a few years for a newly planted hydrangea to establish itself and bloom.
• Q: How do I dry hydrangea flowers?
  • A: The best time to dry hydrangea flowers is when they are mature and starting to feel papery.
    • Cut the stems long and remove the leaves.
    • Hang the flowers upside down in a dark, dry, well-ventilated area.
    • Alternatively, you can dry them in a vase with a small amount of water.
• Q: Are hydrangeas deer-resistant?
  • A: Hydrangeas are not considered highly deer-resistant. Deer may browse on them, especially if other food sources are scarce.
• Q: Are hydrangeas poisonous?
  • A: Hydrangeas contain cyanogenic glycosides, which can be toxic if ingested in large quantities. Keep plants away from children and pets.

Hydrangeas are a rewarding addition to any garden, offering a stunning display of blooms and a wide range of colors and forms. By understanding their needs and providing proper care, you can enjoy their beauty for years to come. Gardencenterpoint.com is here to support you on your gardening journey, providing the information and resources you need to cultivate thriving hydrangeas and create a garden that reflects your unique style. We encourage you to explore the other gardening resources available on our website, including articles on companion planting, soil health, pest control, and much more. Discover the joy of gardening with Gardencenterpoint.com!