Hydrangeas are known for blooming in shades of pink, blue or white and are one of the few types of flowers that can change color. While the white varieties do not change color, pink and blue tones can be affected by the soil in which they grow. In this article you will find out what you should fertilize your hydrangeas with for blue flowers and how the color changes.
Fertilizing hydrangeas for blue flowers: how to change the color?
The secret to the color change in hydrangeas lies in the aluminum content of the soil. Most soils contain enough of it, but if the soil pH is high, the aluminum is not available to the plant. The more alkaline the soil, the pinker the flowers will be. At neutral pH, some varieties remain pink while others show a hint of blue. To bloom blue, hydrangeas need acidic soil with a pH of 5.5 or less. In this article we will explain how you can ensure the necessary conditions for blue flowers using home remedies.
For an acidic base, add coffee grounds
When you fertilize your hydrangeas with coffee grounds, you are actually changing the pH of the soil and therefore the colors of their flowers. Adding coffee grounds naturally makes the soil more acidic, which can lead to blue flowers. But this only applies to certain varieties such as Hydrangea macrophylla, Endless Summer, Everbloom and Forever & Ever.
Before fertilizing the hydrangeas with coffee grounds, it is recommended to test the pH of the soil. If you have very alkaline soil, it will take a lot of effort to produce even the slightest blue color. But if you have a neutral soil, you will be able to change the color of your flowers.
You can either work the coffee grounds into the soil or simply sprinkle them on the soil. Or if you have a compost pile, you can incorporate the coffee grounds into your compost and use them to naturally fertilize the hydrangeas every 6 months.
After fertilizing the hydrangeas with coffee grounds, you should regularly check the acidity of the soil to ensure that it reaches the desired level. As soon as you stop adding coffee grounds, the hydrangeas will return to their original color.
Fertilize hydrangeas with vinegar for blue flowers
Another home remedy you can use to lower soil pH is vinegar. Just be sure to maintain the acidic soil over a long period of time, which could be difficult if rainwater washes out the vinegar.
For this reason, we recommend planting your hydrangeas in containers that are under a protective roof. Use diluted apple cider vinegar or white vinegar in a ratio of 20 parts water to one part vinegar,to water the flowersand make sure you only treat the base of the plant as the acid could burn the leaves.
You should fertilize the hydrangeas with vinegar for several months to achieve the desired results.
Changing the color of hydrangeas with alum
The easiest way to acidify the soil and the hydrangeasto color blue, alum should be used, which is available in the pharmacy. Mix 3g of pure alum with 1L of water, stirring the solution well until the powder dissolves. Soak the soil around your hydrangeasaround in springas soon as the plant begins to grow. Repeat the process every four weeks during the growing season to maintain acidity. It is best to use lime-free water. You will achieve the best results with rainwater.
Can blue hydrangeas turn purple?
If you have blue hydrangeas, you can easily adjust their color to turn them purple. Simply treat the soil with garden lime in the fall before the growing season. This will lower the acidity, so you should be careful. If you add too much garden lime, your hydrangeas will turn pink.
How long does it take for hydrangeas to turn blue?
Large hydrangeas can take months to change color, so you may not see the results until the next bloom season. It is best to start fertilizing in late autumn.
Sometimes some flowers will change color and others won't. So be patient and fertilize the soil again as needed.
Also be aware that hydrangeas planted near concrete are much more difficult to turn blue.
Another factor for the color change is the water quality and pH value. Hard water contains many dissolved minerals such as magnesium and calcium and is therefore alkaline, which can affect the blue discoloration. Use rainwater for watering instead to ensure bright blue hydrangeas next year.
