Cultivation Information Floriculture
The best temperature is around 19°C. To reduce length growth a day temperature of 18°C and a nighttime temperature of 20°C is recommended. Towards the end of cultivation it is of advantage to reduce the temperature by 2 bis 3°C, this leads to a stronger colouring and a more stable structure.
Supplementary light is of advantage for early sets. One should not illuminate for more than 16 hours per day, though (8 hours darkness minimum). The optimum is 14 hours with a daylight total of 60 klxh. This applied for at least the first 30 to 40 days per set results in a corresponding shortening of cultivation time.
Cultivation time can be reduced by another 8% (average) through gassing with CO² Begasung. The optimum concentraton is 900-1100 ppm during light hours. At night gassing is not necessary, as it is effectless.
At the beginning of cultivation it is essential to get N into the flower, because after overwintering there is nearly no N in the soil anymore. It is important to pay attention to a high share of nitrate, because it is accessible immediately to the plant. We recommend to fertilize balanced or rather with emphasis on N-K. For blue varieties it is important to use low-phosphorous fertilizers, because phosphor influences the availability of AL-sulphate negatively.
Furthermore we recommend to especially fertilize with iron at the beginning, because especially the early hydrangeas develop an iron deficiency quickly.
We work with a pH-value of about 4.2 for the blue hydrangeas, therefore we recommend a single fertilization with AL-sulphate of 1.5% (15g/L water) during the first 3 to 4 weeks. (Please only use this concentration for AL-sulphate, not for potassic alum!)
Please spray the hydrangeas directly after the initial forcing once against botrytis, because in early cultivation putrefaction may occur. Furthermore a treatment against snails is of advantage especially for white hydrangeas.
Besides Alar the growth retardant Desmel has proofed effective in recent years. It is important, though, to consider the concentration. For hydrangeas Desmel is authorized for leaf spots, very important in view of the new regulation laws. For regulation of length growth concentrations of 0.02 bis 0.03% are usable without problems. The frequency and possible increase of the concentration are very much dependent on the cultivation or climate management and the weather condition. We recommend a cautious approach to a higher concentration. Furthermore, one should stop using Desmel shortly before the petals appear, because it can cause discolouration.
If you have any further questions, please feel free to contact us. Please note that the aforesaid information can only be recommendations and that we do not take any liability for any damages.
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