Want to add a little excitement to growing your hydrangeas this year and make them bloom in different colors? It’s not only fun to do – it’s far easier than you might think!
Hydrangeas are well loved for their full, showy blooms and deep green leaves. They add a splash of color to any garden with flowers that can appear in shades of blue, pink, purple, white, or even green. Even better, their ability to thrive in different climates makes them a popular choice for many gardeners as well.
But what makes certain hydrangeas even more special is that their flower color isn’t always permanent. Big leaf hydrangeas, in particular, can actually change color depending on the acidity or alkalinity of the soil.
How To Make Your Hydrangeas Bloom In Different Colors
With the right soil adjustments and fertilizers, you can influence the color of hydrangea blooms. While this process requires a little patience, the results can be both beautiful and rewarding. It’s something that we have enjoyed trying with a bit of success over the last few years here with our hydrangeas at the farm.
The good news is that by simply selecting the right fertilizers and soil additives, you can take control of your hydrangea’s bloom color and create a garden filled with the shades you love most! This means that if you have blue flowers but would prefer pink – or vice versa – you can likely make the change just by modifying the soil’s pH and nutrients.
It’s important to note this doesn’t work with all hydrangea types. Some varieties, such as mophead and lacecap can shift between pink and blue, all depending on the soil conditions. However, white hydrangeas will always stay white, no matter what is added to the soil.
What Causes Hydrangea Blooms To Change Color
Many people believe that soil pH alone determines hydrangea colors, but the real factor is aluminum in the soil. More to the point – it is the ability of the plant to absorb aluminum that will affect the bush’s bloom color.
Although pH does not directly change the color, it does play a key role because it controls whether the plant can take in aluminum or not. Adjusting the acidity or alkalinity of the soil changes how much aluminum the roots absorb. And that in turn influences flower color. It may sound a bit complicated – but it’s really not!
When the soil is more alkaline, with a pH above 6.5, aluminum becomes unavailable to the plant, and the flowers turn pink. When the soil is more acidic, with a pH below 5.5, aluminum is absorbed, leading to blue blooms.
If the soil falls in a neutral range between these two, the flowers often take on a purple hue or a mix of pink and blue. And if you want a softer shade of purple? For this, making small adjustments to bring the soil closer to neutral can create a blend of both colors.
Checking The Soil For A Starting Point
Before trying to change the bloom color of your hydrangeas, it’s a good idea to test the soil to see where the pH level currently stands. Having this information allows for better adjustments rather than making random changes. A simple soil pH meter is an inexpensive and quick way to get a fairly accurate reading. Affiliate Link: Soil pH Meter, MS02 3-in-1 Soil pH Tester Gardening Tool
Changing the color of hydrangea flowers takes time. It may take several weeks or even months before any noticeable difference appears. It is also important to wait before adjusting the soil for newly planted hydrangeas.
These plants need time to settle and develop strong roots before being exposed to additional treatments. Allowing them to grow through at least one full season before making any changes will also help keep them healthy.
Turning Blooms Pink
When it comes to turning hydrangea blooms to a different color – let’s start with getting pink blooms.
If you want hydrangeas to bloom pink, the soil needs to be less acidic so the plant absorbs little to no aluminum. One way to do this is by using a fertilizer that is rich in nitrogen and phosphorus. Nitrogen helps increase the pH level, while phosphorus blocks aluminum and also supports healthy flowering.
Another way to raise the pH is by adding garden lime. This natural soil additive gradually increases alkalinity, which helps stop aluminum absorption. To keep pink flowers throughout the season, garden lime or a high-nitrogen fertilizer should be applied in early spring and again in the fall. Affiliate Link: Jobe’s Organics Garden Lime, Lime Powder Soil Amendment
For a natural alternative, crushed eggshells can also help reduce soil acidity. However, they work very slowly and may take a year or more to have an effect.
Turning Hydrangea Blooms Blue
If you prefer blue hydrangea blooms, the soil needs to be more acidic. Using a fertilizer with low phosphorus allows the plant to take in more aluminum, which encourages blue flowers. Affiliate Link: Jobe’s Organics Granular Soil Amendment
Another way to lower soil pH is by adding sulfur. This element helps increase acidity while also supporting strong foliage and deep blue blooms. Coffee grounds can also be used to raise soil acidity naturally.
For best results, apply sulfur, coffee grounds, or an acidic fertilizer in early spring and again in the fall. Transitioning from pink to blue can be more difficult than the other way around, but with consistency, it is still very possible.
If changing the soil in your garden proves challenging, growing hydrangeas in pots can offer better control over soil conditions. Here’s to having a little fun with your hydrangea blooms this year changing their colors! If you are looking for more care tips for your hydrangeas, see What To Do With Hydrangeas In The Spring – 3 Simple Chores For Bigger & Better Blooms! Happy Gardening – Jim & Mary.
Old World Garden Farms
Jim and Mary Competti have been writing gardening, DIY and recipe articles and books for over 15 years from their 46 acre Ohio farm. The two are frequent speakers on all things gardening and love to travel in their spare time.
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