Hydrangeas are among the most beautiful shrubs in the garden. With their magnificent flowers, they immediately become an eye-catcher and their preference for partial shade makes them one of the most popular plants for the front garden. Depending on the variety, garden hydrangeas bloom between June and September and enchant with lush flower umbels in white, pink, red, blue, violet and green. But what makes this ornamental shrub so special is its ability to change flower color. In the article we reveal why this is and how the hydrangeas can be dyed blue.
What changes the color of hydrangeas?
Hydrangeas change color (except the white-flowering types) depending on the pH of the soil in which they grow. The more alkaline the soil, the pinker the flowers. This means that pink hydrangeas can be turned blue if the acidity of the soil is increased.
Not all species can be dyed blue
Hydrangeas can only bloom blue under certain conditions. In addition to the acidic soil, the variety plays a crucial role. Only those varieties that contain a specific plant pigment called delphinidin can be dyed blue.
If you purchase a new hydrangea, pay attention to the plant label. It is usually noted there whether a color change is possible or not for the respective variety. The plant itself can also tell you whether it is a chameleon or not. To do this, you should take a closer look at the flower color - if the hydrangea blooms pale pink, the color change is possible in most cases. Species with white or intense pink-red flowers, on the other hand, cannot be dyed blue.
Blue coloring is possible with these hydrangeas:Farm hydrangeas, garden hydrangeas and plate hydrangeas, e.g. B. the varieties “Forever & Ever” and “Endless Summer”.
Here's how to color your hydrangeas blue
The first thing you need to do if you want to change the flowering color of your hydrangea is to measure the acidity of the soil, that is, determine the pH. To do this, you should first take a sample.In this articlelet's explain how this works.
To promote blue hydrangea flowers, you should grow the plant in soil with a pH of 5.2 – 5.5. For an intense blue color, the pH value should even be below 5.0. If your soil is more alkaline, you may want to try lowering the pH to change the flower color to blue. You can use various means for this.
Change color with home remedies
There are various home remedies that can help keep soil pH low.Coffee grounds, for exampleis perfect for plants that require acidic soil. The same applies to leaf compost and needle litter. You can incorporate these additives into the soil to lower the pH of the soil. It is also recommended that you plant the hydrangeas in hydrangea or rhododendron soil, which are also acidic.
But be careful! Some home remedies, such as vinegar and vinegar essence, have a low pH value, but are completely unsuitable if you want to make the soil more acidic. Vinegar is actually a real plant killer, so you should stay away from it when using yourDye hydrangeas bluewant.
Dye hydrangeas blue with alum
In order for the hydrangea to have blue flowers, the plant still needs the mineral alum. It contains aluminum ions, which are responsible for changing the flower color to blue. You can either buy alum in its pure form at the pharmacy or, even easier, yourselfsuitable hydrangea fertilizerpurchase one that is already enriched with the mineral.
But using pure alum is not difficult either. The powder is simply added to the irrigation water - 3 g per liter of water is sufficient. Jethe water is less limestone, the better, rainwater is of course best suited. From the beginning of May, you should water the hydrangeas with the alum solution once a week for 4 to 5 weeks.
The color change works best for hydrangeas in a pot because the pH value of the soil is easier to regulate in a pot.
How long does it take for the flower color to change?
To maintain uniformly blue flowers, your soil's pH will likely need to be adjusted regularly. To do this, carefully work acidifying soil amendments into the top layer of soil around the root when you normally fertilize your hydrangeas, usually in early spring. Even if you start from alkaline or neutral soil and try to make it more acidic, keep in mind that your hydrangeas won't suddenly turn blue overnight. It will probably take several applications of fertilizer to make the soil acidic enough, and if your hydrangeas have already bloomed pink, you may not see blue flowers until next year.
