I can't give you any advice other than to tell you that my shady border is filled with the Lace Cap Hydrangeas, and it really is shady. I do water them well, not very good at feeding them, I leave the dead heads on all winter to protect them from frost until the fresh shoots start to show in the spring. Then I chop the heads off. I must be doing something right because they look glorious at the moment. So I don't know if any of that helps you but good luck.
Yes they did all flower last year and I left flowers on until the springtime before cutting back. They are not nearly out in flower yet but they are there on 3 only. Let’s hope more come but interesting help from you all thanks for that. Always good to get others opinions.
Giggsie make sure you cut only the dead heads off next year, and not any new growth. I look forward to you telling us you have loads of flowers next year.