Incremental gradient increase


I’m trying to create a hedge which gradually increases in height. I’ve used the sandbox tool to contour the top but I’m getting gaps at the sides. Is there a tool that would fill these in nicely please? I’m aware that, being on a curve, I could just draw the lines the make the faces required and smooth/soften but I’m doing this repeatedly so looking for a quicker solution.

Thank you

Screenshot 2020-04-02 at 10.51.43|690x209

Ah yes - that makes much more sense - thank you!!!