Brown leaves on hydrangeas are not uncommon. Sometimes, care errors, the weather, or the location are to blame.
You can get this under control. Water the plants regularly, especially in dry weather. Hydrangeas have high nutrient requirements. A lack of certain nutrients such as nitrogen or potassium can lead to brown to yellow or reddish leaves, and sometimes the plant also stops growing. Too much fertilizer can also cause discolored leaves. Use a special hyDRangea fertilizer to lower the pH value of the soil, for example, which also lowers the pHvalue of the plant. You should only carefully acclimate them to the increasing sunlight outdoors. If you want to keep them in pots indoors and move them outside, you should only closely monitor them. Do not water them over the leaves, otherwise the sun can act like a magnifying glass. If they are exposed to too much direct sunlight, their leaves can burn in spots and develop brown or yellow spots. Water them thoroughly, especially during hot summer months.