Water proof fabric is always best if you want to cover some portions of a pallet board to create a pocket or holding space for potting purposes! This method will work great while you are targeted a whole pallet board to get a vertical garden or planter! Add the nails or use the staple gun to assemble the cloth to wood sides to avoid leakage of potting soil you are to put in later!
If you are not going with this scheme, then tear apart some portions of pallets and readjust the slats again to create holdings in pallets to gain a planter setup! If you provide bottoms to dice sections of pallets, they can serve you as better potting levels just in no time! Every picture is clear and leads to a unique idea and one can easily pull out some tricks and tips from them to go with his own way while getting a sublime planters out of pallets!