Cultivation Information Nurseries

To produce compact and sturdy plants we recommend to largely open the vents. The cooler the hydrangeas are being cultivated, the more stable their structure becomes and the stronger the colouring will be. Frost exposure has to be prevented, though.

The vent temperature should be adjusted to the average night temperature. The maximum difference should not exceed 5-8°C. That means, amounts the average night temperature to 5°C, the vents should open during the day at 10-12°C latest. Is the difference too large, length growth is fostered unnecessarily and the hydrangeas develop a softer structure.

It is important as well to take good care to ventilate unnecessary moist away. Should the vents stay closed during a cold period with high air humidity it is recommended to ventilate once or twice a day, otherwise again a soft structure will be the result.

The soil should have a rough structure and be well permeable to air. All big soil suppliers have readymade hydrangea mixtures and we recommend these. Please feel also free to ask one of our sales representatives nearby. They offer soil as well and know the requirements of hydrangea soils.

The soil should be fertilized with approx. 3 kg/m³ Osmocote Exact Standard (15-9-12-2,5Mg) 5-6M and 200g/m³ Micromax (trace elements).

For blue hydrangeas the pH-value should be adjusted to 4.5-4.8 and maybe 1kg/m³ Al sulfate should be added. Or you immerse the hydrangeas into an Al sulphate solution before potting.

For red, pink and white hydrangeas no Al sulphate may be used and the pH-value should be adjusted to 5.5.

We work with a pH-value of around 4.2. Therefore we recommend a single fertilization with al sulphate of 1.5% (15g/L water) befor potting. (Please use this concentration only with Al sulphate, not with potassic aluminum.) It is as well possible to immerse the hydrangeas into a stock solution before potting, but please note that the foliage and the buds have to be rinsed off with clear water, then.

Complimentary fertilization should only be done in coordination with a consultant of the company ICL, because water quality can make a difference as well.

If the technical equipment makes it possible to refertilize with a dosatron or EC-regulated, we recommend to give “Universol weiß” (15-0-19-2Mg) once or twice per week at a dosage of 1.0g/l at the beginning of cultivation (after rooting in the container). After every second to third fertilization Universol weiß can be substituted by Universol orange (16-5-25-3.4Mg).

It is advisable to additionally solute 200g Tenso Iron ( Fa. Yara) per every 25kg Universol into the stock solution, to ensure enough iron is given and to receive a bright colouring of the foliage.

If you do not have the technical equipment we recommend to refertilize with Osmoform (19-5-13-2Mg), ca. 1.5-2.0g/l (after rooting in the container).
As required, leaf-feeding is possible as well. Here, it is advisable to start the culturing with Peters Professional Foliar Feed (27-15-12), given in several treatments with 1.0g/l. Near the end of cultivation time it should be switched to Peters Professional Combi-Sol (6-18-36-3 +SpE).



To prevent unwanted lenght growth hydrangeas may be treated with Alar (0.1-0.4%) or Desmel/Tilt (0.02 – 0.03%) up to once a week. The frequency and a possible increase of the concentration is very much dependent on the cultivation and climate management as well as the weather. Therefore, we recommend to approach higher concentration cautiously. Furthermore, the treatment with Desmel/Tilt should be stopped shortly before the petals can be spotted, because it can lead to discolouration. 

In the cultivation of hydrangeas usually no plant protection is necessary. Only aphids and botrytis can become a problem. Concerning aphids, Pirimor is well compatible to hydrangeas, and against botrytis Switch and Teldor proved to be worthwile. The compatibility has to be checked in each case, though, because the plants stage of development is decisive.

This recommendation has been written in cooperation with the company ICL. Therefore, please contact your ICL advisor with any questions about substrate fertilization or additional fertilization.

We hope we could help you into a good start for the hydrangea season. If you have any further questions about the above mentioned or other topics, feel free to contact us. Please bear in mind that we can only give recommendations and will not take any liability in case of damages or in licensing questions.


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