Do You Make Garden Grids™ Longer Than 8 Squares?

We don't, but you can connect multiple Garden Grids™ together with our Garden Grid™ Manifolds and short garden hoses to cover larger areas! Here's a video showing how they work and you can find manifolds here and our short garden hoses here.
We also have specific recommendations for garden bed sizes like 4x10 here, 4x12 here, and 4x16 here.