Hydrangeas have high nutritional requirements. Here you can find out if and why hydrangea fertilizers are really necessary and what the differences are.
The genus Hydrangea includes 70 to 80 species, several of which are very popular in our gardens. Although they please almost everyone with their characteristic inflorescences, some species are real divas when it comes to their location, hydrangea care and nutrient supply.
Hydrangeas don't always show their best side everywhere. We explain why hydrangeas benefit from a specific fertilizer, what it consists of and how organic, mineral, blue coloring and organic hydrangea fertilizers differ.
Why do hydrangeas need a special fertilizer?
The nutrient requirement of hydrangeas is very high overall. Of the three main nutrient elements, nitrogen (N) and potassium (K) are required in large quantities, while phosphorus is required to a lesser extent. In addition, the need for iron is increased in many species. Some hydrangea species - such as the velvet hydrangea (Hydrangea sargentiana) and the climbing hydrangea (Hydrangea petiolaris) - react quickly to a suboptimal care and nutrient supply with a Flowering failure or frost damage.
In addition to the right supply of nutrients, the properties of the soil or potting soil are crucial for the successful care of hydrangeas. For example, their high water requirements require humus-rich soil that can store a lot of water. At the same time, there must be no waterlogging, because the plants also suffer from this. Almost all hydrangea species also require a fairly low soil pH. This not only influences the coloring of the flowers of the hydrangea (Hydrangea macrophylla), but in particular the ability of all hydrangeas to absorb nutrients. An unsuitable pH value of the soil can therefore trigger malnutrition. Since the soil properties are affected by the type of fertilization, choosing a special hydrangea fertilizer is a practical way to ensure a he althy and well-floweringEncourage plants.
What is hydrangea fertilizer made of?
Hydrangea fertilizers can be mineral, organic or organo-mineral. While mineral fertilizers only contain the raw nutrients as quickly soluble fertilizer s alts, the nutrients in organic fertilizers are bound in natural structures that are only released through biological and chemical processes in soil life. Organic fertilization maintains and nourishes soil life and can thus improve soil properties. Organic-mineral hydrangea fertilizers combine both types of fertilizer and therefore have both a high rate of action and a natural long-term effect while maintaining soil qualities.
Tip: Because hydrangeas love acidic locations, some special fertilizers even contain substances that acidify the soil. The "alums" are a group of sulfuric acid compounds made from metal ions, sulfate and water. As alum dissolves in soil water, the pH drops due to the release of protons (H+ ions). This effect also leads to the blue blossom of the hydrangea (Hydrangea macrophylla) - but only for a short time. The creation of a constantly acidic environment around the hydrangea has a more lasting effect. If the soil pH is not highly acidic, the peasant hydrangea will display its flowers in classic pink or white.
Comparison of hydrangea fertilizers
The type of fertilization has a strong influence on the vitality of your hydrangeas. However, it is not just the nutrients that are important, as you will learn below.
Mineral Hydrangea Fertilizer
Mineral hydrangea fertilizers in liquid and solid form provide a precisely defined selection of nutrients. In addition to nitrogen, phosphorus and potassium, they sometimes also contain a selection of trace nutrients. It is possible to supply your hydrangeas with such a fertilizer, but regular use will have the following negative effects:
- The micronutrient reserves in the soil or the potting substrate can become exhausted, which can result in deficiency symptoms on the plant that are difficult to recognize.
- The high concentration of nutrients promotes the breakdown of humus, but no new material is brought in to build up humus. As a result, the humus content of the fertilized soil decreases, and with it hisQuality.
- If used incorrectly, mineral fertilizers can also cause fertilizer damage: Susceptibility to frost and failure to bloom are possible.
Blue Hydrangea Fertilizer
Because the almost bright blue coloring of farmer's hydrangeas inspires many garden owners, they are willing to buy so-called "blue coloring" hydrangea fertilizer or "blue hydrangea fertilizer". These acidify the soil with aluminum sulphate for a short time. It can even be purchased pure, so you can make blue-dyeing hydrangea fertilizer yourself. However, caution is required when using it: aluminum is a cell toxin that damages plant roots. It only becomes available at low pH values and can severely inhibit root growth in excessive doses. You can find out more about the blue coloring of hydrangeas here.
Note: If you want to learn more about how to fertilize your hydrangea properly, we are sharing our pro tips with you here.
Organic Hydrangea Fertilizer
An organic fertilizer for hydrangeas not only fertilizes the plant but also the soil. The organisms in the root zone of the hydrangea are fed and release the fertilizer nutrients for the hydrangea. In addition, material introduced is built up into new humus molecules in the course of humification. In this way, any degraded humus is replaced and the soil qualities that are so important for the hydrangea - water retention capacity, soil aeration and nutrient availability - are promoted. However, one problem with organic hydrangea fertilizers can be their slow rate of action. Forward-looking fertilization is necessary because the release can take up to a month, depending on the weather and the associated microorganism activity.
Organic Hydrangea Fertilizer
Organic fertilizers are organo-mineral fertilizers with an organic certificate. Like all organo-mineral fertilizers, they combine the advantages of the two opposite types of fertilizer, but rely on organic components for the most part. The mineral components serve to supplement and optimize the effect and must also be permitted in organic farming. Our Plantura organic hydrangea fertilizer carries such an organic certificate. In addition, only plant-based raw materials are used. The production is therefore many times more environmentally friendly and the application is possible for a broader mass of users without a bad conscience - because this fertilizer has nothing to do with resource-devouring factory farming. Of theNutrient content is adapted to the specific needs of hydrangeas and, in addition to the main and trace nutrients contained, iron is also contained in a slightly higher dose to prevent the quite common iron deficiency in hydrangeas.
You can find more information about our animal-free organic hydrangea fertilizer here.
Make hydrangea fertilizer yourself: fertilize hydrangeas with coffee grounds and co.
Bargain foxes can also make fertilizer for hydrangeas themselves. For example, stable manure slurry is fast-acting and rich in all three main nutrients. Extra iron can be brought in with nettle manure. The production of these liquid manures takes a few weeks. Aside from a bit of patience, you don't need much more than a large, watertight container - like a mason's bucket. Compost is not necessarily suitable for hydrangeas: it often has too high a pH value, which can lead to problems with nutrient absorption in the Hydrangea genus. But you can still use your organic waste for hydrangea fertilization: In a Bokashi bucket, there is no composting, but fermentation. The contained lactic acid bacteria acidify your organic waste. The result can be hidden under a layer of mulch around the hydrangeas, for example. Due to the fermentation in advance, surface composting then takes place very quickly and nutrients are provided.
Last but not least, we present you with a home-made hydrangea fertilizer that is absolutely suitable for everyday use: Coffee grounds from the French press or the filter are slightly acidic and provide nutrients to a lesser extent. Together with a nutrient-rich fertilizer, however, it forms the perfect basis for humus formation and thus for soil improvement around your hydrangeas. You can find more precise information on how to produce your own fertilizer in our associated special article.