Hello! The slight deterioration can be caused by the stress suffered during planting, temperature fluctuations between day and night during the last period, a possible nutrient deficiency, a pest attack (check carefully for the presence of pests) etc. In view of the recent planting, we recommend the use of a fertilizer to stimulate rooting, improve the quality of the soil and support the plants’ resistance to various stress factors: or , by watering at the roots, according to the recommendations on their label. 2-3 treatments can be carried out at 2-week intervals. Afterwards, two weeks after the treatments are completed, it is recommended to use a special hydrangea fertilizer such as , which prevents nutrient deficiencies. More tips and information about hydrangea care can be found in our article: Hortensia, planting guide and care work.