Last Updated on January 3, 2022 by Grow with Bovees
Every time I buy blue hydrangeas, they produce pink flowers the following year.
I hear people say that you can change the hydrangea color by altering the soil.
Is this really so?
Yes, fortunately, changing the color of hydrangeas is possible, and fairly straighforward, by adding things to the soil.
Unlike most plants, the color of the commonly grown hydrangea (Hydrangea macrophylla), as well as the intensity of the shade, is influenced by the pH level of the soil.
What Makes Hydrangeas Blue?
Hydrangeas planted in acid soils with a pH of approximately 4.5-5.5 will have produce light blue, through brilliant blue…to deep blue blooms and every shade in between.
What Makes Hydrangeas Pink?
Hydrangeas planted in alkaline soils with a pH of 7.0 and higher, will mostly produce flowers in various shades of pink.
Is Changing the Hydrangea Color Easy To Do?
Yes, you can turn your hydrangea from pink to blue and likewise make a blue hydrangea turn pink
But a lot depends on which hydrangea variety it is and from which of the hydrangea cultivars it derives.
Can I Change the Acid or Alkaline Levels of My Soil?
Unfortunately, it is difficult to change a very alkaline soil to an acid soil — and vice versa.
However, when your soil pH levels are more neutral, or only mildly acid or alkaline, then they can be altered, and the plants will produce the required flower color from deep blue hydrangea blooms to deep pink hydrangea blooms.
How to Make Hydrangeas Blue
It’s actually incredible that one can turn Hydrangeas blue. However, by applying various types of chemical acidifiers — such as aluminum sulfate or Espoma GSUL6 (amazon link) — at a strength of 1 — 4tbsp per gallon of water — regularly to the soil will change the pH of the soil, making the soil more acidic to encourage blue flowers, as will adding compost materials like; coffee grounds, egg shells, peat moss and pine needles which act as a natural soil acidifier and thereby produce acidic soil for beautiful blue blooms
It should be noted that sulfate sulfurs such as; ammonium sulphate or gypsum should be used rather than untreated elemental sulfur, which is more difficult for plants to take up and won’t actually make the soil acidic as it is not water-soluble.
How to Make Hydrangeas Pink
The regular use of small quantities of agricultural lime/garden lime in neutral soil will make it more alkaline to encourage pink blooms. This can be added in granular form on the surface of the soil at a strength of between 2.5 — 5lbs per 100 square feet depending on your soil type. The addition of some mushroom compost can also help to make the blooms pink.
These chemicals must be added regularly to the soil from late autumn to early spring, February is an ideal month to start.
Once the flower heads have formed, it is usually too late to influence the color of most hydrangeas.
The soil pH is quite easy to check using an electronic soil tester.
It should also be noted that the soil’s ph needs to be maintained throughout the growing season so that you are not disappointed by any hydrangea color change. Nothing would be more disappointing than your beautiful blue color turning pink.
Where to Grow Hydrangeas
Hydrangeas need a very rich growing medium and should therefore be planted into well-prepared beds with plenty of compost, old cow manure, and good garden soil.
You can use your hydrangea flowers for cut flower displays, which, with the correct cut hydrangea care, should last for a couple of weeks.
You can also grow hydrangeas in pots, using some good quality bagged potting compost, where you will have an easier job of controlling the soil pH levels. You should be sure to transplant your hydrangeas into new, larger pots as they grow bigger.
If you want to have your hydrangeas producing flowers in both blue and pink shades — and your soil is relatively neutral — it is better to plant your hydrangeas in separate areas so that you can apply the right hydrangea fertilizers.
Varieties of Hydrangeas
Traditional Varieties of Hydrangeas
You will find that the older varieties of hydrangeas — which, on the whole, have fairly small flower bracts — do not have such vibrant shades as the newer hybrids.
New Hydrangea Varieties
However, there are now certain red and white varieties that are completely colorfast so with those varieties, no change in soil conditions will make your hydrangea change color.
A great deal of work is being done on hybridizing to expand the range of hydrangea colors, hence the reason why florist hydrangeas look so amazing.
Color in hydrangeas is no longer just a matter of; blue hydrangea flowers, purple hydrangeas or suddenly pink hydrangeas that start appearing when soil conditions turn your blue hydrangea pink.
Although it has to be said that it’s quite exciting when see your hydrangea bloom color is changing due to what you fertilize it with!
Hydrangea Bloom Colors
White hydrangeas include; Oakleaf hydrangeas, Hydrangea paniculata ‘Great Star’ and Hydrangea paniculata ‘white lace’, some of which change to pinkish tones as the flowers age.
Blue Hydrangeas include; Endless Summer Hydrangea, Blue Mophead Hydrangea, Tiny Tuff Stuff Hydrangea.
Pink Hydrangeas include; Invincibelle Spirit, Hydrangea serrata ‘Golden Sunlight’, Endless Summer Bella Anna.
Tips And Hints
If you are having problems with your hydrangeas not blooming, then check out our possible solutions, but first of all, start by being sure to remove any dead hydrangea blooms.
Plus, they are greedy, so ensure you use fertilizer on hydrangeas.
Many of the modern hydrangea hybrids do not seem to change as easily as the older types.
Therefore, if you want to have really good colors, it is advisable to buy named hybrids whenever possible.
If you are aiming for a blue colour then be sure to avoid your hydrangeas growing in places with concrete close by as this often has lime in it which can leach into the soil and foil your efforts!
Astoundingly, it is well within most people’s capabilities to actually change the color of their hydrangeas whether by using products from gardener’s supply stores or by simply using household organic materials!