The Martha Stewart Show, May 2007
Make the cement mixture in bin using one gallon peat, one gallon "Portland" cement, and one gallon perlite. Wear mask to avoid breathing dust and use gloves when mixing, as concrete can burn hands.
Slowly add approximately 2 1/2 quarts of water as if you were making dough, being sure to add the last part of water slowly. Humidity can affect how much water you need.
The mixture should clump in your fist and hold its shape.
Transfer mixture to a smaller bin. Use any container to shape. If you use metal, oil the interior to prevent binding. Shape mixture into bin. To avoid suction, use a flexible container. Pack very tightly to bottom and sides.
Place a lid on bin to prevent mixture from drying unevenly, which affects curing. Place in plastic bag.
Leave in bin for 2 to 3 days to dry.
Remove planter from bin. Turn it upside down, being careful not to drop it. Dust loose concrete from the top edges.
Let this air dry for another week.
To create optional drainage, drill holes in bottom.
Fill planter with shallow-rooting arrangement.
One gallon peat
One gallon "Portland" cement
One gallon perlite
Large and small bins
These lightweight concrete containers are ideal for succulents or alpine plants, which have adapted to growing on rocky ledges and shallow soil.