This traditional favorite is a must-have in any garden, and new cultivars have made hydrangea cultivation simpler than ever.
Generally speaking, blue or lavender-blue hydrangea flowers are produced by acidic soil, which has a pH lower than 6.0. Pinks and reds are encouraged by alkaline soil, which has a pH above 7.0. The blossoms turn purple or bluish-pink at a pH of 6 to 7.
Add aluminum sulfate or garden sulfur to your soil to reduce pH levels. Use ground lime to increase the pH. To ensure that the pH of your soil is within the desired range, retest it according to the instructions on the product you’re using.
Do all hydrangeas have a soil-related color change?
The pH of the soil affects the color of hydrangeas. While most other colors will change, white hydrangeas won’t. The color of the flowers will be pinker in more alkaline soil, while redder blossoms may occasionally appear in severely acidic soil. Your flowers will be bluer the more acidic the soil is.
Does hydrangea blossom color depend on the pH of the soil?
A gardener from Lincolnton, Georgia, where I was raised, asked me my first inquiry as the agricultural and natural resource Extension agent for Columbia County. Her springtime planting of pink hydrangeas turned blue blossoms by the time summer rolled around.
She knew how important it was to add lime to the soil to change the pH level and, in turn, the hydrangeas’ color. She required details regarding the type of lime and application technique, though.
The greatest gardening starts with a soil sample, as any representative from the University of Georgia Cooperative Extension will inform you. Knowing the nutrients and pH level of the soil from a soil sample takes the guesswork out of how much lime or fertilizer is required.
At a pH of 6 to 6.5, the majority of important plant nutrients are easier to obtain. Plants may be unable to take up nutrients from the soil if the pH is either too high or too low. Because of the chemistry of the soil, the plant cannot access or absorb the nutrients. Numerous symptoms can accompany this issue, but in the case of hydrangeas, the bloom color alters.
The presence or lack of aluminum compounds in hydrangea flowers causes color variance. Blue color indicates the presence of aluminum. When present in modest amounts, the color might range from pink to blue. The blossoms are pink if there is no metal present.
Because soil pH affects the availability of aluminum in the soil, flowers’ colors are indirectly affected. Blue flowers are produced when the soil is acidic (pH 5.5 or below), as aluminum is more readily available to the roots.
Because Georgia’s soils tend to be acidic, the majority of hydrangea flowers are blue. Aluminum is less available in soil that has a pH of 7.0 or above, which is considered to be alkaline. Usually pink, the blooms in this soil are.
I advised my gardeners to spread one cup of dolomitic lime over ten square feet of soil and water it in to restore the hydrangeas to their former pink color. However, it can take a year using this technique to detect a noticeable improvement in blossom color.
By soaking the soil in liquid, changes can be made more quickly. In one gallon of water, dissolve one spoonful of hydrated lime. In March, April, and May, soak the surrounding soil with the solution. The solution should not be applied on the leaves as it may harm them.
There are numerous brands that sell dolomitic limes, including Pennington, Greenacres, Lilly Miller, and Green Earth, among others. Additionally, there are numerous hydrated lime product brands available, including Hi-Yield, Bonide, Hoffman, and Lees. All are wise decisions.
Although homeowners in Georgia frequently deal with acidic soil, alkaline soils do exist. Distribute half a cup of wettable sulfur per 10 square feet and water it in to gradually turn pink flowers blue.
Again, liquid soil drenches are a quicker approach to effect the transformation. In the months of March, April, and May, saturate the soil around the plant with a solution of one tablespoon of aluminum sulfate in one gallon of water. Make sure to keep the solution off of the leaves.
If you want to plant hydrangeas in fall, you need first improve the soil where you plan to do so. Apply 50 pounds of decomposed organic material per 10 square feet and thoroughly work it with a tiller or shovel into the top 8 to 12 inches of soil.
Create a hole for the plant that is twice as large as the root ball. Avoid planting too deeply. Make sure the root ball’s top is parallel to or just above the soil’s surface. After planting, give the area plenty of water and add 3 to 5 inches of mulch.
Throughout the growing season, hydrangeas react to numerous sparing doses of fertilizer. They are thirsty plants that work best in landscape zones with modest water use.
Is it possible to modify the hue of every hydrangea?
A hydrangea’s color can fluctuate drastically, and occasionally, they even display various colors on the same bush. Ulrich Doering/Alamy Stock Photo provided the image.
Only certain hydrangea species, primarily those related to H. macrophylla or H. serrata, can change the color of their flowers. The typical belief is that soil pH and flower color are connected. Although the quantity of aluminum a plant can access in the soil—which is governed by pH and phosphate levels—determines the color, as Michael Dirr describes in his book Hydrangeas for American Gardens.
Unless phosphorus levels are high, a lower pH permits aluminum to be soluble and absorbed by plants, and blue flowers are more common. Aluminum is locked up at a higher pH, and pink flowers are more common. When blossoms first open, shades of cream to green are also visible, and as flowers get older, the tones might alter.
Why are the colors on my hydrangeas changing?
Some bigleaf hydrangeas (Hydrangea macrophylla) have the unusual capacity to switch from pink to blue, or vice versa, in the blossom color. The amount of aluminum in the soil that the plant can utilize has caused this alteration. Aluminum is easily accessible in acidic soils, and hydrangea roots can take this mineral in. However, plants are unable to absorb the element into their roots in alkaline soils. Your soil is too alkaline if you’ve ever planted a gorgeous blue hydrangea and the next year it blossomed pink.
Bigleaf hydrangeas can be made to change color by altering the pH of the soil, but only if they were pink or blue when they were first planted. Hydrangeas that are white will never change.
Get a soil test
Get a professional soil test, whether you plant in the ground or in containers, to determine the exact acidity or alkalinity of your potting mix or soil. You can purchase a home test kit or a pH meter from the garden center to obtain a pH measurement, albeit they are not quite as precise as a professional test (and you might not receive N-P-K levels). After that, you can appropriately adjust your soil to control the bigleaf hydrangea’s color.
How to get a professional soil test
You might be able to receive a referral to a lab where you can send a soil sample for an accurate test from your county extension office or nearby colleges. You can also visit this website to get a list of laboratories that conduct soil tests: Program for North American Proficiency (NAPT)
Why did my blue hydrangea turn pink?
Popular flowering garden shrubs like hydrangeas regularly confound us by altering the color of their flowers after they have been planted. And since the color change is probably a slow process, it can take a few years before you notice it has happened.
Can the color be changed back? is one of the first queries that a new student or client for landscape design makes. Is the hydrangea in trouble? is a different issue.
Will my Hydrangea die if it changes colour?
If the only problem is the color change of the blue to pink or pink and purple to blue blossoms, it is doubtful that your hydrangea is dying. Hydrangeas are often simple plants to maintain. As we’ll see below, your Hydrangea’s color change could have underlying factors that could ultimately harm the shrub’s general health.
Why has my Blue Hydrangea turned Pink?
After being brought home and planted in the garden, not all hydrangea varieties will change the color of their flowers. The soil determines whether they do.
The bushes that are most frequently seen in gardens are hydrangea macrophylla, also referred to as mop-head hydrangeas. Due to the rounded flower balls on them, they are known as mop heads. Lace cap hydrangeas, in contrast, have smaller, fertile flowers that are encircled by bigger, sterile sepals.
These two hydrangea kinds will almost certainly change color depending on the pH of your soil. With a pH meter or test kit from a garden center, you can quickly determine how acidic or alkaline your garden soil is. Also see the blogs listed below.
The impact this has on the levels of aluminum in the soil, rather than just the acidity of the soil, is the real cause. Aluminum levels rise with soil acidity, turning pink and purple hydrangeas blue as a result. The blue flowered should persist on soil with a pH of 6 or lower.
If you want to be sure of retaining the blossom color, the tip is to check the soil pH before you buy a mop-head or lace cap Hydrangea.
How do I Keep my Blue Hydrangea Blue?
Alternately, place your mop-head hydrangeas in a peat-free ericaceous compost-filled ericaceous bed. Rhododendrons, azaleas, and your hydrangeas might all be planted together. A floral display from April to October can be expected if you group all the acid-loving plants together.
How do I Keep my Pink Hydrangea Pink?
by having soil that is alkaline, or has a pH of 7 or above. An acceptable pH range of 6.57 should be achieved; cover with compost made from used mushrooms to help keep the soil alkaline.
Why not grow your hydrangeas in containers if your soil is acidic? One on each side of your entrance door might look really attractive.
What about my Purple flowered Hydrangea?
A good query! I’m not sure I can readily respond to that question because it depends not just on the soil but also on the shrub’s ancestry. Because of this, some purple hydrangea blossoms do not turn pink when planted in acidic soil.
Why has my Blue Hydrangea turned PinkMore Solutions to the Problem
Why not buy a Hydrangea that won’t change color when planted to make your life easy from the start? Not all hydrangeas exhibit the same tendency for blossom color change.
For instance, even in macrophylla cultivars, white and green flowering variations have a tendency to remain the same color.
Hydrangea petiolaris
Likewise called the climbing hydrangea. It is a robust, self-clinging climbing shrub that is cultivated for its heads of white flowers.
It takes time to establish itself, but once it does, it can grow vigorously and may need to be pruned if you don’t want it to cling to your gutters!
Dark green foliage changes to butter yellow in the fall before wintering as a tracery of branches. The young twigs have a lovely reddish brown sheen.
HydrangeaPruning Tips
Of course, its not just about why your blue Hydrangea turned pink. You could be perplexed as to why there aren’t any flowers at all despite pruning the bush.
Although hydrangeas don’t need much trimming, adopting a strategy that promotes new wood will keep them from being too woody. Continue reading to make sure you pruned your shrub correctly for its type.
Between February and early March, you can prune a lot of summer-flowering deciduous shrubs, typically those that bloom on the growth of the current year. One hydrangea that has to be pruned frequently is hydrangea paniculata.
On the wood from the previous year, mop-head hydrangeas bloom. If you live in a mild climate, you can deadhead by cutting back to a strong pair of shoots as early as late February, or you can wait until March.
What next?
Now that we know the reason why the blue hydrangea turned pink, we can determine which blossom colors are still the same as when you first acquired the plant.
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Gardens to visit with Hydrangeas
The Holehird Gardens, home of the Lakeland Horticultural Society, includes a Hydrangea walk with more than 300 species if you’d like to take in hydrangeas in their entirety. In July and August, this is the place to go if you’re still not convinced about the beauty of hydrangeas because you’re likely to locate one for your own yard. Check out a description of one of my visits in the list of blogs below.
Even though they don’t have the same diversity of species as those available at Holehird, other locations of the UK with acidic soil frequently have attractive displays of hydrangeas. One particularly evocative example is the shady drive at Portmeirion, which has lighting Hydrangea plants tracing your path. There are more gardens worth seeing on the west coast of Scotland, in Ireland, and in Cornwall.
Visit Plews Potting Shed blogs, such as the ones below and our monthly Tipsheet, for additional gardening guidance and inspiration.
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