How do you make a pre casted concrete edge of a garden?

Answer 1

First of all if this is in reference to a DIY project the border wouldn't strictly be precast,,,BUT it is quite simple.

Form a BOX/Trench, with plywood and bracing lumber,,,A FORM in which to pour concrete mix. Quickcrete will work.

Mix as directed, pour, let set, remove form, and get about having fun with the garden.

Rev. Steven