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How to Change Hydrangea Color to Blue, Pink, or Purple

Whether you prefer the cool blue hydrangea flowers or the warm pink blooms, with the right soil pH, your hydrangeas can change color and beautify your garden for years to come.

Blue Hydrangea, Pink Hydrangea, Hydrangea Colors, Hydrangea flowers

Hydrangeas are cherished for their stunning blooms, which can range in color from blue to pink and even purple. One of the unique features of certain hydrangea varieties, particularly Hydrangea macrophylla (Bigleaf Hydrangea), is their ability to change color based on the soil’s pH levels. This guide will provide you with detailed information on how to manipulate the soil to achieve your desired hydrangea color, along with essential care tips to keep your plants healthy and vibrant.

Understanding the Science Behind Hydrangea Color

Soil pH and Hydrangea Color

The color of hydrangea flowers is primarily influenced by the availability of aluminum ions in the soil. Here’s how it works:

Acidic Soil (pH below 6.0): In acidic conditions, aluminum ions are more readily absorbed by the plant roots, resulting in blue flowers.

Neutral to Alkaline Soil (pH above 6.0): In neutral or alkaline conditions, aluminum becomes less available, leading to pink flowers.

Color Variations

  • Blue Hydrangeas: Achieved in more acidic soils, typically below pH 5.5.
  • Pink Hydrangeas: Result from neutral to alkaline soils, typically above pH 6.0.
  • Purple Hydrangeas: Can occur in soil with a pH between 5.5 and 6.0

Which Hydrangea Change Color?

Not all hydrangea varieties will react the same way to soil amendments. Here are the hydrangea plants to consider:

Hydrangea macrophylla (Bigleaf Hydrangea)

This hydrangea species is a cherished garden choice. This deciduous shrub features a rounded growth habit, showcasing large, lush leaves and long-lasting summer blooms. It is categorized into two main types: Mophead Hydrangeas, characterized by their large, vibrant flower heads, and Lacecap Hydrangeas, which display flat clusters of radiant sterile florets encircling small, fertile ones.

  • Native: Native to Japan, China, Korea, and Southeast Asia.
  • Bloom Time: Typically blooms from late spring to early fall.
  • Size: Grows 2 to 6 feet (60-180 cm) tall and wide.
  • Popular Varieties: Nikko Blue, Merritt’s Supreme

Hydrangea serrata (Mountain Hydrangea)

This graceful deciduous shrub has a rounded growth habit and showcases delicate lace-cap flowers in flattened clusters from early to late summer. While reminiscent of the Bigleaf Hydrangea, it exhibits a more refined appearance and features smaller flowers and leaves. The elegant blossoms of some cultivars bloom in abundance and possess the enchanting ability to change color three to four times throughout the season, adding dynamic beauty to any garden.

  • Native: Native to Japan and Korea.
  • Bloom Time: Blooms from early to late summer.
  • Size: Typically grows 2 to 4 feet (60-120 cm) tall and wide.
  • Popular Varieties: Diadem, Bluebird, Tuff Stuff

Please note that the color of white hydrangeas is not influenced by soil pH; their flowers remain white and cannot be changed. 

Kardinal Violet Hydrangea, Bigleaf Hydrangea 'Kardinal Violet', French Hydrangea 'Kardinal Violet', Mophead Hydrangea 'Kardinal Violet', Hydrangea macrophylla 'Kardinal Lilac', Hydrangea macrophylla CardinalKardinal Violet Hydrangea – Hydrangea macrophylla or Bigleaf Hydrangea

Testing Soil pH

Before making any adjustments to your hydrangea’s environment, it’s crucial to determine the current pH level of your soil. Here’s how to test it:

  • Purchase a Soil pH Test Kit: These kits are available at garden centers or online. Look for ones that are easy to use and provide accurate results.
  • Collect Soil Samples: Take samples from various locations around your hydrangea plants. Ideally, collect samples from the root zone to get an accurate reading.
  • Follow the Instructions: Most kits will require you to mix the soil with a provided solution and compare the color change to a pH scale included in the kit.

Turning Hydrangea Color to Blue (Increasing Soil Acidity)

If your soil is more alkaline and you desire blue blooms, follow these steps:

Add Aluminum Sulfate: This amendment lowers pH and provides aluminum ions to the plants. Apply according to package instructions; typically, a rate of 1 tablespoon per foot of plant height is effective.

Use Elemental Sulfur: This is a gradual method that may take several months to show results. Incorporate it into the soil in the spring or fall, mixing it well into the topsoil.

Mulching: Use mulch made from pine needles, shredded oak leaves, or other acidic materials to help maintain lower pH levels. This also protects the roots and retains soil moisture.

Nikko Blue Hydrangea, Blue Hydrangea, Hydrangea Flowers, Hydrangea macrophylla, Bigleaf HydrangeaNikko Blue Hydrangea – Hydrangea macrophylla or Bigleaf Hydrangea

Turning Hydrangea Color to Pink (Decreasing Soil Acidity)

To achieve pink blooms, you’ll need to raise the soil pH. Here’s how:

Add Lime: Incorporate agricultural lime or dolomitic lime into the soil according to the instructions on the package. This will help raise the pH and reduce the availability of aluminum ions.

Test Soil pH Regularly: After making adjustments, retest the soil pH every few months to ensure you are moving towards your desired level.

Hydrangea Macrophylla 'Peppermint', Bigleaf Hydrangea 'Peppermint', Hydrangea 'Peppermint', Hydrangea 'REI13', Forever & Ever Series, Pink Hydrangea, Blue Hydrangea, Bicolor HydrangeaPeppermint Hydrangea – Hydrangea macrophylla or Bigleaf Hydrangea

Hydrangea Macrophylla 'Peppermint', Bigleaf Hydrangea 'Peppermint', Hydrangea 'Peppermint', Hydrangea 'REI13', Forever & Ever Series, Pink Hydrangea, Blue Hydrangea, Bicolor Hydrangea

Duration for Color Change

Keep in mind that altering hydrangea color is not instantaneous. Expect to see results within weeks to months. Changing blue flowers to pink is generally easier than the reverse.

Additionally, it’s advisable to wait until the plant is about two years old to ensure it can handle the stress of any adjustments.

Now that your hydrangeas are showcasing stunning blue, pink, or purple blooms, consider drying them to preserve their beauty for crafts, floral arrangements, or home decor. This way, you can enjoy their vibrant colors long after the blooming season has ended.

Troubleshooting Common Problems with Hydrangea Flowers

Hydrangeas are beloved for their beautiful blooms, but sometimes gardeners encounter issues that prevent these flowers from reaching their full potential. Here are some common problems related to hydrangea blooms, along with their causes and solutions:

Lack of Blooms

Hydrangeas do not produce flowers or have very few blooms. Possible causes:

  • Incorrect Pruning: Pruning at the wrong time can remove flower buds. Hydrangeas that bloom on old wood should be pruned immediately after flowering, while those that bloom on new wood should be pruned in late winter or early spring.
  • Insufficient Sunlight: Hydrangeas generally thrive in partial shade to full sun, but the specific light requirements vary by species. Insufficient light can lead to weak growth and fewer blooms.

Poor Flower Quality

Flowers are small, lack vibrancy, or appear wilted. Possible causes:

Discoloration of Hydrangea Flowers

Flowers are turning brown or losing their vibrant color.Possible causes:

  • Sunburn: Too much direct sunlight can scorch blooms, especially in hotter climates.
  • Nutrient Imbalance: A lack of nutrients or an incorrect soil pH can lead to color fading.

Wilting Flowers

Possible Causes:

  • Overwatering: Waterlogged soil can lead to root rot, causing wilting. Check the drainage of your soil; ensure that it drains well and does not retain excess water.
  • Underwatering: Inconsistent watering can also result in wilting. Maintain a consistent watering schedule, allowing the top inch of soil to dry out between waterings.

Flowers Turning from Blue to Pink (or vice versa)

Hydrangea flowers are changing color unexpectedly. Changes in soil acidity can lead to color shifts. For instance, blue flowers may turn pink if the soil becomes less acidic.

Test your soil pH regularly, especially after adding amendments, and adjust accordingly to maintain your desired color.

Premature Fading

Blooms fade quickly after opening. Possible Causes:

  • High Heat: Prolonged exposure to high temperatures can cause blooms to wilt and fade prematurely. Position plants where they receive some afternoon shade to reduce heat stress.
  • Lack of Water: Inadequate watering during hot spells can exacerbate fading. Water deeply during hot weather and consider mulching to retain soil moisture.

Hydrangea macrophylla, Bigleaf Hydrangea, Big Leaf Hydrangea, Blue HydrangeaAll Summer Beauty – Hydrangea macrophylla or Bigleaf Hydrangea

Frequently Asked Questions

Do coffee grounds change the color of hydrangeas?

Yes, coffee grounds can help make soil more acidic, which can contribute to turning hydrangeas blue. When added to the soil, coffee grounds release nitrogen and may slightly lower the pH, promoting blue coloration in varieties like Hydrangea macrophylla.

How does vinegar change the color of hydrangeas?

Vinegar, particularly white vinegar or apple cider vinegar, can lower soil pH when applied to the soil, making it more acidic. This can encourage blue blooms in hydrangeas. However, it’s important to use it sparingly, as excessive acidity can harm the plants.

Does apple cider vinegar turn hydrangeas blue?

Yes, apple cider vinegar can help turn hydrangeas blue by lowering the soil pH when applied. Like white vinegar, it should be used carefully to avoid excessive acidity that could harm the plant.

Will egg shells turn hydrangeas blue?

Eggshells are primarily made of calcium carbonate, which can raise soil pH and make it more alkaline. As a result, they may contribute to pink blooms rather than blue. If your goal is to achieve blue flowers, you should avoid using eggshells in the soil.

How quickly can you turn hydrangeas blue?

The speed at which you can turn hydrangeas blue depends on several factors, including the current soil pH and the methods used. Typically, changes can be observed within a few weeks to a couple of months after applying acidic amendments. However, for significant color changes, especially if starting from a neutral or alkaline base, it may take a full growing season or longer for optimal results.

Guide Information

Hardiness 3 - 9
Heat Zones 1 - 9
Plant Type Shrubs
Plant Family Hydrangeaceae
Genus Hydrangea
Exposure Full Sun, Partial Sun
Season of Interest Spring (Late), Summer (Early, Mid, Late), Fall
Maintenance Low
Water Needs Average
Soil Type Clay, Loam, Sand
Soil pH Acid, Alkaline, Neutral
Soil Drainage Moist but Well-Drained
Characteristics Dried Arrangements, Cut Flowers, Showy
Attracts Butterflies, Hummingbirds
Landscaping Ideas Patio And Containers, Hedges And Screens, Beds And Borders

Garden Examples

A Lovely Contemporary Garden Idea
A Majestic Walkway
An Elegant Shady Corner
Compare All Hydrangea
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Explore Great Plant Combination Ideas
Hydrangea
Guides with
Hydrangea
While every effort has been made to describe these plants accurately, please keep in mind that height, bloom time, and color may differ in various climates. The description of these plants has been written based on numerous outside resources.

Guide Information

Hardiness 3 - 9
Heat Zones 1 - 9
Plant Type Shrubs
Plant Family Hydrangeaceae
Genus Hydrangea
Exposure Full Sun, Partial Sun
Season of Interest Spring (Late), Summer (Early, Mid, Late), Fall
Maintenance Low
Water Needs Average
Soil Type Clay, Loam, Sand
Soil pH Acid, Alkaline, Neutral
Soil Drainage Moist but Well-Drained
Characteristics Dried Arrangements, Cut Flowers, Showy
Attracts Butterflies, Hummingbirds
Landscaping Ideas Patio And Containers, Hedges And Screens, Beds And Borders
Compare All Hydrangea
Compare Now
Explore Great Plant Combination Ideas
Hydrangea
Guides with
Hydrangea

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