Can you change the colors of the hydrangea flowers? Yes, it just depends on your type of hydrangea and the pH of your soil.
We will explain how to change from blue to pink or from pink to blue. Keep in mind, this will only work for the blue or pink varieties, so the white flowers cannot be changed to any other color.
The importance of soil pH
Unlike most flowers, Lacecap and Mophead hydrangeas (H. macrophylla) may change color. The gardeners of the eighteenth century were the first to realize this and they experimented by burying rusty nails, serving tea or even chanting spells around your plants.
It is the pH of the soil that determines the color of the flower. Blue ones grow best in acidic soils, while pinks and reds do best in alkaline or neutral soils.
In strongly acidic soils pH less than 5.5, the flowers turn blue.
In alkaline soils pH higher than 7, the flowers turn pink or even red.
In slightly acidic or neutral soils pH 6 to 7, blooms can be purple or a mixture of blue and pink on a single bush.
The white color of the hydrangea is not affected by the pH of the soil. Whites stay white, the color can never be changed, and they generally prefer the same pH conditions as pink and red.
But relationship between color and pH it is more complex than just the numbers on a scale; is the availability of aluminum ions, and the degree to which you can absorb them.
To start, you can do a soil test using a kit that is readily available at a good garden center. Once you know the general pH of your soil, you can adjust it to get the hydrangea flower color of your choice.
To change the hydrangea to the color blue
If your hydrangeas are pink, because your soil is alkaline and you want them to be blue, you need to acidify the soil by increasing the presence of aluminum.
You can achieve this by adding amendments to your soil like pine needles, compost, coffee grounds, and aluminum sulfate, which help the soil to become more acidic over time.
Keep in mind that changing the pH of your soil is a gradual process, and it can take up to a year for the color change to occur.
For aluminum, dilute a solution of seven grams of aluminum per four liters of water. Soak the soil with the solution after the plant begins to grow in spring and repeat twice at intervals, between three and four weeks.
Aluminum sulfate is a colorless salt obtained by the action of sulfuric acid on hydrated aluminum oxide. You can buy it at any garden center.
To change the hydrangea to pink
To increase alkalinity and change the blue flowers to pink, in spring or fall spread ground limestone (dolomitic lime) in a ratio of 4 cups around the plant and water it well, repeating every three to four weeks. Be careful, excessive alkalinity will cause chlorosis or yellow leaves.
Cut hydrangeas
Hydrangea flowers are so pretty, that it is natural to want to cut them to show the different colors in the interior of your house. But so that the flowers do not wilt an hour after they enter the water, you can perform the following trick:
Immerse the cut stems in cold water immediately after cutting. Pour about 2,5 inch of boiling water into a separate container and let it cool for two minutes. Cut the stems to size as you like. Keep the bottom of the stems in the hot water for about 30 seconds, then transfer the stems to cold water. Clever!