For a trough 23 x 45 x 18 centimetres (half the recipe on the previous page for smaller projects):
Tightly cover mould with plastic bags (you can omit this step if mould is made of plastic), tucking in all corners and taping covering into place. Place mould upside down on your work surface. (Or, build trough inside mould; while easier, note that exterior of hypertufa pot will be smoother and less rustic-looking.)
In a wheelbarrow, combine vermiculite, peat moss and Portland cement. Blend ingredients, then add water and mix well with your hands (wear rubber gloves). Mixture should be thoroughly wet and the consistency of cottage cheese.
Starting at bottom of mould (top of hypertufa trough), pat handfuls of mix into place—gently slapping it as you work to remove air bubbles—until it’s about five centimetres thick. (Occasionally check depth with your finger or a stick, then smooth surface back into place.)
If making your trough on inside of container, push and pat mix firmly against bottom and sides of mould.
Once you reach top of mould (bottom of trough), check depth again before smoothing surface with your hand. Then take a flat board (or wide scraper) and draw it firmly across top to level base; you don’t want the trough rocking when you plant it up. (Skip if building container inside mould.)
Poke dowels (or sticks) through mixture to create drainage holes, leaving dowels in place until mixture hardens; jiggle them around every day or so for easy removal at the end. Loosely cover trough with plastic to help keep moisture from evaporating. Mist occasionally during first few days to encourage even curing. After a week, remove plastic and let trough sit, uncovered, for four to five more days.
Turn trough over (hypertufa looks heavy, but is surprisingly light). Remove mould from hypertufa shell. Smooth edges of trough with a carpenter’s file. If it rocks, run file over bottom. Conversely, for a more rustic look for a planter made inside mould, use a wire brush to rough up finish. Ensure drainage holes are unobstructed; if necessary, use a drill or hammer and nail to clear them. Spray trough with a hose to remove any lime that may have surfaced; let it cure for a few more weeks before planting up.