Everything You Need to Know About Hydrangea Flower Colors
Hydrangea colors can be tricky to define due to one fascinating characteristic – they can change color. There are several factors that influence this change, from species to age and, most importantly, the pH of the soil. This article discusses everything you need to know about Hydrangea colors, including the most popular types in each category.
What Colors do Hydrangeas Come In? – The Essentials
Hydrangeas are available in pink, purple, blue, white, and green across several species. Some species change color based on the pH in the soil. Acidic soils will lead some to turn blue, while an alkaline soil will cause your Hydrangeas to bloom pink. Others remain white for most of the season, and several also bloom green for a while before fading to other common colors.
Hydrangeas are commonly known by their genus name and occasionally their previous genus name Hortensia. They are the most used genus in the family Hydrangeaceae, with over 75 species grown worldwide. They are prized for their symbolic value and host of uses and benefits.
Although there is some variation between the popular hydrangea species, only a few are usually grown in home gardens:
- Bigleaf (Hydrangea macrophylla)
- Oakleaf (Hydrangea quercifolia)
- Smooth (Hydrangea arborescens)
- Panicle (Hydrangea paniculata)
- Climbing (Hydrangea anomala subsp. petiolaris)
- Mountain (Hydrangea serrata)
Bigleaf Hydrangeas are a crowd-favorite and the most widely grown species. But each species comes with its own quirks, from uniquely shaped flowers, varying sizes, to different growing zones that make them all beautiful choices for home gardeners.
The Hydrangea genus is native to Asia and the Americas, with each species originating from a slightly different region. Many of the common species are native to North America, growing well in cooler climates and flowering best where the weather is temperate. There is also great diversity in Asia, where many exciting species are natively found in China, Korea, and Japan.
Hydrangeas are generally considered shrubs, featuring large green leaves on dense, short branches. While these glossy leaves provide some interest and coverage across the seasons, these plants are primarily grown for their large flower heads in a range of different colors.
Some species flower from spring (benefiting from fertilizing), but most look their best throughout the summer months and extend into autumn (before needing to be cut back or transplanted), depending on your zone. Due to the extensive interest in these plants, there are many hybrids and cultivars to choose from, bred to have even bigger at better flowers that continue to impress year after year.
Hydrangea flowers are generally classified as mopheads or lacecaps. Mopheads have large clusters of smaller flowers in a pom pom shape, while lacecaps have flat heads with smaller flowers in the center and larger ones toward the edge.
When the temperatures drop, your Hydrangea will lose its leaves over the winter season. Despite the lack of leaves, many will still require winter protection to warm the roots and protect the small buds that will produce new growth and blooms the following season. In spring, when temperatures begin to rise, you will see new growth develop again.
It’s worth noting that hydrangeas are considered toxic, so it’s prudent to wear a pair of gardening gloves throughout the process.
What Determines The Color Of A Hydrangea?
Hydrangeas are perhaps most well-known for their ability to change color. This isn’t a minor color change as the flower ages, as you may see in some other blooms, but a drastic change from deep pink to bright blue.
There are a few characteristics that impact Hydrangea flower color to look out for:
The first defining factor in Hydrangea color is the species. Only two of the few commonly grown species actually have the ability to change color. This includes the most popular Bigleaf Hydrangea (Hydrangea macrophylla) and the Mountain Hydrangea (Hydrangea serrata). Other Hydrangea species will remain the same color no matter the conditions they are kept in, with some only changing color toward the end of the season as the flowers fade.
If you’ve planted a Bigleaf or Mountain Hydrangea, that does not guarantee they will be able to change color. White Hydrangeas will remain white, and even some pink and purple species will remain the same color, not impacted by external conditions. These species can fade to a different color toward the end of the season but will remain their original color during their main blooming period no matter where they are planted. It’s essential to understand your specific type before buying if you are looking for color-changing Hydrangeas.
If you have the suitable species and color, the next and most important factor influencing their color is the pH of the soil. Well, to get more technical, it is actually the presence of aluminum in the soil and how it interacts with the soil pH.
In alkaline soils with a pH of 7 or higher, aluminum particles bond to the soil more frequently, not taken up by the plants. Due to the lack of aluminum, the hydrangea blooms will remain pink. In acidic soils, more aluminum is absorbed and metabolized by the plants, causing them to turn blue.
Most soils have enough aluminum to make the pH distinction enough to change the color. However, in soil that lacks aluminum, your Hydrangeas will always stay pink, no matter the pH.
Temperature can also have an impact on what color your Hydrangeas are and the intensity of that color. Hydrangeas grow best in moderate conditions in USDA Zones 3-7. They prefer cooler weather to warm weather.
If temperatures are too warm, your Hydrangeas will never turn the intense pink, almost red color, nor will they reach deep blue. Instead, they will remain a soft pink, purple or blue, depending on the other factors discussed.
White hydrangeas can also change color to a pink hue when temperatures drop, signaling the end of the flowering season.
Hydrangea Color Varieties
White Hydrangea Flowers
White is arguably the most popular Hydrangea color. The delicate blooms instantly brighten any garden, standing out amongst the deep green foliage. They also make wonderful cut flowers, especially for wedding bouquets or décor.
There are many wonderful cultivars to choose from across the different species. Bigleaf Hydrangeas are generally sold with colored flowers, but there are a few options that remain pure white throughout the season. Lanarth White is one of these, with large lacecap flowers and a hardy growth habit. Fireworks is another option, featuring double blooms that can take on a slight pink or blue tinge depending on soil pH.
Most white Hydrangeas are part of the Hydrangea paniculata species. Flowers in this species have a unique cone shape and are either pure white in color or have a slight hue that makes them appear a soft pastel. Sundae Fraise is one of these, developing a soft pink blush as the flowers mature.
Popular as cut flowers, Smooth Hydrangeas are stunning in white, with rounded heads in stark and eye-catching creamy colors. Annabelle is a beloved white cultivar for its massive flower heads that, despite their size, look incredibly delicate. Incrediball features even bigger flowers and stronger stems than Annabelle to stop the stunning flowers from falling over under their own weight.
Oakleaf Hydrangeas can’t be left off this list either. With names like Snow King, it’s not hard to see why. These Hydrangeas are great for warmer areas as they can better withstand the head without impacting too much on their flowering. Try Alice or Gatsby Moon for stunning white summer blooms.
Blue Hydrangea Flowers
Blue flowers are somewhat of a mystery, not at all common but incredibly sought after by ornamental gardeners. Their rarity is explained by the difficulty of flowers to produce blue pigment, the reason why only 10% of all flowers around the world have blue petals. Other flowers may appear in certain lighting but are generally considered purple.
If you’re looking for that beloved blue color, look no further than Hydrangea macrophylla and Hydrangea serrata. In the right soil conditions, there are many varieties that cover different shades of blue, from pastel to an intense deep blue that most gardeners only dream of.
Most blue Hydrangeas fall under the Bigleaf category. The most sought after has to be blue members of the Endless Summer Series, grown for their long-lasting flowers and long blooming season.
Twist and Shout is one member of the series with lacecap flowers in a stunning blue tone. But that’s not all there is to choose from. Look out for these other blue Bigleaf cultivars in your area:
- Générale Vicomtesse DeVibraye
- Big Daddy
- Nantucket Blue
- Nikko Blue
- Let’s Dance Rhythmic Blue – a mix of blue and purple
- Mathilda Gutges – the deepest blue of all the Hydrangeas
Although less common, you can also look to Mountain Hydrangeas for your daily dose of blue color. These blooms are usually a more delicate pale blue rather than the intense blue of some Bigleaf Hydrangeas. Look out for Bluebird, Blue Billow, or Tuff Stuff Ah Ha and snatch them up quickly as they sell out fast.
As these species have the ability to change color, make sure your soil is acidic and has enough aluminum to keep these blooms blue. There are also specialized fertilizers and potting soils available designed to maintain the color of the flowers.
Pink Hydrangea Flowers
Pink hydrangeas are a firm favorite among home gardeners, in shades from the lightest blush pink to an almost red vibrant hue. In fact, most of the cultivars labeled as red hydrangeas are just a really dark pink color, intensified in the suitable soil and climate conditions.
As with blue Hydrangeas, the go-to flower for its longevity and gorgeous shape is the Endless Summer series. With the right soil and conditions, you can make these flowers appear any way you want. Other Bigleaf Hydrangeas in the pink category are Zorro or the incredible Miss Saori, boasting white petals with pink edging.
For a deeper pink flower color, opt for the Mountain Hydrangea Preziosa. Not only are the blooms a bright and intense pink, but the foliage provides interest of its own, changing to a deep burgundy color in fall.
Other species also provide attractive options for any kind of garden. For lovers of Oakleaf Hydrangeas, Gatsby Pink will meet all your needs.
Green Hydrangea Flowers
The final Hydrangea color to consider is green. While some gardeners don’t appreciate when their previously white, pink, or blue blooms transform to a shade of green, many gardeners actually look forward to it. Thanks to this interest, a few cultivars have been developed that remain green for most, if not all season long. These are also very popular in floral arrangements, complementing green foliage incredibly well.
The most popular of all the green Hydrangeas is Limelight, a Panicle Hydrangea with gorgeous whitish-green flowers. Although they are considered the best and longest blooming green type, they often take on a shade of turn white and eventually turn pink at the end of the season. Little Lime is the next best thing – just like Limelight, only more compact.
If you can get your hands on one, you can also try Pistachio and Candy Apple. While they generally don’t stay green as long as Limelight, they are great ways to add a fleeting complementary green hue to your perennial garden.
Hydrangea Colors FAQs:
What determines the color of a hydrangea?
There are many factors that impact Hydrangea color, starting with the species and cultivar. Some change color with age, with others are affected by the pH and presence of aluminum in the soil. Climate can also have an impact, with warmer weather, frequent watering, and higher levels of sunlight frequently resulting in minor color changes.
Do coffee grounds change the color of hydrangeas?
As used coffee grounds have the ability to lower the soil pH and make it more acidic. Adding coffee grounds to your soil well before the flowering season can help your Hydrangeas bloom blue. It’s best to conduct a soil test before you start to make sure you know what soil pH you’re dealing with and work it deeply into the soil to stop it from hardening on the surface.
Do rusty nails turn hydrangeas blue?
Another gardening hack states that rusty nails also have the ability to lower soil pH and add iron to the soil, turning hydrangeas blue. Unfortunately, there’s little evidence to support this theory. When placing rusty nails in the soil, very few nutrients are released, changing almost nothing. Burying nails in the soil is also dangerous for gardeners and garden guests, so it’s far safer to avoid using them at all.
Will vinegar turn hydrangeas blue?
As vinegar is acidic, many people suggest adding it to the soil to turn hydrangeas blue. However, as vinegar is water-soluble, it will not impact soil pH in the long term. It’s also not safe for your garden environment, deterring beneficial wildlife and attracting problematic pests.
Hydrangea Flower Colors – The Final Word
These color-changing beauties are staples in any ornamental garden, treating you to a kaleidoscope of pink, purple, blue, white, and green throughout the season.
To enjoy the fruits of your labor for longer, see our essential guide to drying and preserving hydrangea flowers at home.