If hydrangeas don't look as pretty as usual, it may be because they're lacking fertilizer. But how do you properly fertilize hydrangeas?
Hydrangeas (Hydrangea) are among the flowers that can be found in almost every garden. No wonder, because they enchant us again and again with their blooms and the unbelievable variety of varieties and colors. In addition, there are commercially available hydrangea varieties for almost every location. There are some for the blazing sun and some for mostly shady places. So everyone can have hydrangeas in their garden.
But just planting the hydrangeas is not enough. Of course, hydrangeas also need proper care. Since they have a high water requirement, you must always water your hydrangeas sufficiently, for example. But don't forget to fertilize, because this is the only way for the flowers to develop fully.
It's all about pH
Sometimes hobby gardeners are surprised that their hydrangeas suddenly no longer have intensely colored flowers. Especially with blue varieties, it is often noticeable that the flowers eventually turn pink. There is a very simple reason for this: the color of the flowers depends heavily on the degree of acidity, i.e. the pH value of the soil. Blue flowers are formed at a low pH of 4 to 4.5, while pink and red varieties prefer slightly acidic soil with a pH of 5.5. But the aluminum oxide content also has an influence on the flower colour.
If you now change the acidity, you can also change the color of the hydrangea blossoms. Water a little more with rainwater or low-lime tap water, then blue varieties keep their beautiful color, while you can change pink specimens to blue. If you then work some peat into the soil, you can even intensify the effect. A larger quantity of low-lime water and peat therefore lower the pH value of the soil. In addition, you should then give a fertilizer that contains aluminum sulfate.
If the pH value of the soil is optimal, the hydrangea can best absorb the nutrients from the fertilizer. If you want to use a special fertilizer for hydrangeas, you must pay attention to whether it contains aluminum or notnot if you want some coloring of the buds. If you want to turn the buds blue, you'll need to use either a high-potassium, low-phosphorus fertilizer or a high-aluminum sulfate fertilizer:
By the way:
The blue coloring is only possible with violet and pink peasant hydrangea varieties, as they contain the coloring agent delphinidin. White varieties do not have this and therefore remain white.
Fertilize hydrangeas properly
The right choice of fertilizer:
After first discussing the influence of the pH value on the flower color, we now turn to the perfect fertilization of hydrangeas. It is best to use a special hydrangea fertilizer. Alternatively, you can use fertilizer for azaleas or rhododendrons.
Hydrangeas definitely need a fertilizer that contains a lot of nitrogen but little phosphorus. Universal fertilizers are therefore not suitable for hydrangeas, as they usually contain a large amount of phosphorus, and it is precisely this that the plants do not get. If there is an oversupply of phosphorus, blue flowers can turn pink.
The right time for fertilizing:
You need to fertilize your hydrangeas for the first time in spring. The plants growing in the garden should be given a solid fertilizer. A second fertilization is then necessary in early summer. You should use a long-term fertilizer.
Hydrangeas in pots should always be given a liquid fertilizer. This should be done at regular intervals from March to early August. Once in full bloom, you can stop fertilizing because far fewer nutrients are needed from then on.