How to Make a Plant Box as a Partition

Make your molds from two refrigerator boxes. You’ll need one larger box for the outer mold and a smaller “nesting” mold for straight, even planter walls. Cut the boxes down as needed with the box cutter. Make new seams with strapping tape.

Create rounded corners in both molds by cutting apart and then reshaping the corner cardboard with strapping tape.

Put on the gloves and dust mask. Sift the peat moss through the screen to remove chunks. Measure out the dry ingredients. Mix together roughly three parts peat moss, three parts perlite, two parts portland cement and a handful of fiber mesh in the wheelbarrow.

Add water slowly, mixing the hypertufa with your hands, until you achieve the consistency of cookie dough. When you squeeze a handful, it should hold together well. If the mixture is wet, your container won’t be strong.

Place 3 inches of hypertufa on the bottom of the larger mold, packing it firmly. Put the smaller mold on top of the mixture, centering it inside the larger mold. Add more hypertufa between the two molds, packing it firmly. Once all four sides are filled, flatten and smooth the top and round the edges.

Cover the planter box with plastic and leave it to cure for 36 to 48 hours. The plastic will help retain moisture and dry more slowly. During this initial curing phase, the planter shouldn’t be touched or moved.

Test the hypertufa’s hardness after a couple of days. If you can scratch the surface with your fingernail -- try this on an inside surface – it’s still too soft. But, if you need a screwdriver to scratch it, carefully remove the mold. Use the wire brush to smooth corners and any rough edges.

Cure the planter in the shade for several more weeks. Leach it thoroughly with water to remove alkali, which will damage plants. A quick way to do this is to fill the empty planter with water frequently -- it’s porous -- for several weeks.