We have a number of hydrangeas growing in pots some are cutting taken from older plants. The largest of the is very prolific and produced large colorful blooms last year. It is growing very well but most of the leaves have a dark brown discoloration at the tip, but the younger plants have not been affected. Looking forward to your reply in due course. Best regards Ivor Giles p.s I don't have the technology or expertise to upload photos
Hydrangea Growing in Pots
Certified GKH Gardening Expert
The brown leaf edges can be caused by watering issues. If they plant is let to dry out and then watered, it can cause the leaf edges to turn brown.
Keep the container Hydrangea consistently watered.
Excess fertilizer can also cause the edges of leaves to turn brown/black.