In order for hydrangeas to grow dense and bushy and bloom profusely, you need regular fertilizer applications. The hydrangea is a bit tricky and not every fertilizer is suitable for supplying the plant with nutrients. In this article you can find out which fertilizer is suitable for hydrangeas and when you should preferably fertilize.

Hydrangea nutritional needs

Hydrangeas are among the plants that place very special demands on the soil and have a relatively high nutrient requirement. The shrubs need a lot of nitrogen and potassium, as these nutrients have a direct impact on flowering. In addition, the plants must be adequately supplied with minerals such as iron, sulphur, manganese and zinc, as these are often not available in sufficient quantities in the soil.

Suitable fertilizers

In order to meet the nutrient requirements of the hydrangeas, the plants must be fertilized with a nitrogen-rich chemical or organic complete fertilizer that also contains little phosphorus. Many commercially available universal fertilizers are unsuitable for flowering plants because the phosphorus content of these agents is far too high. In the case of blue hydrangeas, this causes, among other things, the flowers to turn pink or pink again.

Mineral Fertilizers: Convenient to use

You can get special mineral fertilizers for hydrangeas in well-stocked garden shops. Alternatively, special fertilizers are also suitable for rhododendrons or azaleas. These fertilizers optimally supply the hydrangea with all the nutrients required for healthy plant growth and rich flowering.

Thanks to the fertilizer that is well incorporated into the soil, the necessary nutrients are immediately available to the plant. However, this has the disadvantage that the fertilizing effect can decrease after a short time. Only if you fertilize regularly and exactly according to the manufacturer's specifications can an even supply of the plant be ensured.

Liquid special fertilizers for hydrangeas are very suitable for feeding potted plants. Fertilize regularly as indicated on the packaging in order to optimally supply the plant with all the nutrients.

Organic fertilizers - the natural alternative

More and more garden lovers want to avoid using chemical fertilizers and therefore prefer to use organic fertilizers. These provide the hydrangea with all the necessary nutrients over a longer period of time, but they need some time to have an optimal effect. For this reason, you must carefully plan the timing of fertilizing with organic fertilizers. Organic fertilizers are environmentally friendly and, since many of the products can be produced by yourself, they are an inexpensive alternative to other fertilizers.

horn shavings and horn meal

These fertilizers are made from cattle horns and hooves that have been crushed or ground.

  • Horn meal: less than a millimeter in size
  • Horn semolina: Grain size from one to five millimeters
  • Horn shavings: (32.93€) grain size over five millimeters

The nitrogen content of this fertilizer is around 12 to 15 percent, the phosphorus content is less than one percent. Horn shavings must first be broken down by the soil organisms and only decompose slowly. Over-fertilization is thus almost impossible. In the case of horn meal, the decomposition time is a few days, while coarse horn shavings take several months to completely decompose.

In order to optimally supply the hydrangea with all nutrients, we recommend spreading horn shavings on lean and dry soil in combination with humus.

Humus: Nutrient-rich, deep black compost soil

Humus is a highly effective garden fertilizer that tiny microorganisms produce from garden and green waste. Within a year, properly prepared compost turns into a pleasantly fragrant, moist, crumbly and very nutritious substrate that you can work directly into the soil.

Hydrangeas love coffee grounds

Coffee grounds contain many minerals and, if applied regularly, shifts the pH of the soil to the acidic range preferred by hydrangeas. Worms and microorganisms also love coffee grounds, so this fertilizer noticeably improves the soil structure.

However, it is not enough to spread the coffee grounds around the hydrangea. Work the fertilizer well into the soil so that it can develop its full effect.

Special fertilizer turns the flowers blue

Without special fertilization, hydrangeas bloom pink, white or red. The coveted blue color only occurs when aluminum compounds and potassium alum are present in the soil and the substrate has a pH of 4.0 to 4.5.

To keep your blue hydrangea looking beautiful:

  • Special bloom fertilizers for the blue coloring are only effective for pink flowering varieties
  • The pH of the soil must not exceed 4.5 (test strips)
  • The pH value can be shifted to the desired acidic range with rhododendron soil.
  • Only water the hydrangea with rainwater.

The right time to apply hydrangea blue is spring. Constant application of fertilizer according to package instructions is necessary, otherwise the flowers will gradually turn pink again. However, these two-toned flower balls can look very distinctive.

The right time for fertilization

When the days are getting longer again and the spring sun is getting stronger and warming up the soil, this is the best time to supply the hydrangea with fertilizer for the first time of the year. Loosen the soil around the plants with a digging fork and dig in some humus mixed with horn shavings. Since the horn shavings only decompose slowly, it is sufficient if you fertilize the hydrangea a second time in June.

Alternatively, outdoor hydrangeas and hydrangeas in tubs can be fertilized in spring and early summer with a long-term mineral fertilizer. You should also incorporate these fertilizers into the soil.

Smaller potted hydrangeas need to be watered regularly with liquid fertilizer once a week during the growing season, which runs from March to August.

All hydrangeas, regardless of whether they are grown in containers or outdoors, should only be fertilized until the end of the growing season at the end of August. This is the only way for the shoots to fully mature before the start of winter. If fertilized for too long, sufficient shoot closure is not guaranteed and there is a risk of frost damage.

Never fertilize hydrangeas with blue grain!

Blaukorn is one of the fast-acting compound fertilizers and is relatively inexpensive. The fertilizer contains as much phosphorus as nitrogen and is therefore completely unsuitable for fertilizing hydrangeas. Blue hydrangeas that are fertilized with blue grain will turn pink again within a very short time. In addition, blue grain flows very uncontrolled. Therefore, if possible, refrain from fertilizing the neighboring plants of the hydrangea with blue grain.

tips and tricks

Hydrangeas often suffer from chlorosis caused by iron deficiency. This trace element is hardly present in many soils. Iron chelate fertilizers and watering with rainwater can help here.

Category:

Vegetable garden