If you have wanted to work with concrete in the garden but are hesitant because of the weight of the final projects, let me introduce you to hypertufa! Hypertufa is traditionally made with a mix of peat moss, perlite, and Portland cement. It can be molded into many forms and is much lighter than a solid concrete structure. In addition, they are porous and are therefore a good choice for plants who need good drainage.
Concrete planters and hypertufa troughs are easier to make than you might think.
The only difference: one is smooth (concrete) and one is rustic and rough (hypertufa). The following shows the steps to make a concrete bowl.
*NOTE: To make this project in hypertufa, add a mix of 2 parts perlite, 2 parts peat moss, 1.5 parts Portland cement, and enough water to have it just stick together. Mix well and adjust the ingredients as need until you can form a ball in your hands that sticks together without being able to squeeze water out.
First, decide on a shape. Squat shapes are easiest for beginners and make wonderful troughs and low bowls for succulents and other plants typically grown in rocky areas.
Create a pair of moulds (inside and outside) by selecting or fashioning two identical shapes, one approximately 25 percent smaller than the other. For example, two plastic bowls in similar shapes that fit inside each other with a little more than an inch (about 3 cm) space between them. Cardboard boxes also work well. Spray plastic containers with nonstick cooking spray. If using cardboard, line your moulds with plastic.
Mix your concrete according to package directions. To create a hypertufa blend, add approximately 30 percent peat moss, cocoa husks, wood chips or sawdust to the mix prior to adding water. This will result in a stiffer mix. A plain concrete mix will not be as rigid.
Fill the bottom and sides of your moulds with your mix of choice to a thickness of 11/2 in. (4 cm). Insert lengths of sticks cut the same depth as your mix to create drainage holes.
Place your inner mould on top. Press down until the bottom and sides are of an even thickness. Position stones or other weights inside the top mould to hold it down. Tap the mould several times to remove air bubbles.
Allow your pot or trough to dry for several days. Then release the concrete from the moulds and remove drainage sticks. Allow the containers to cure, preferably outside where rain can wash over them for several weeks before planting.