The ingredients:

• 1 part portland cement
• 1 1/2 parts coarse perlite
• 1 1/2 parts screened spaghnum moss

(Spaghnum moss should be rubbed through hardware cloth attached to a frame. You'll want to wear a dust mask for this operation.)

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Sand may be used in place of the perlite, but the resulting trough will be much heavier.

The method:

• Cover the pan or box you're using as a form with plastic.
• Make a loose-fitting mask of chicken wire in the shape of your mold.
• Mix the dry ingredients in a mortar box or other suitable container. Add water until the mixture is about the consistency of (moist)cottage cheese.
• Cover the plastic-covered form with about an inch of the prepared mix.
• Position 3-5 pieces of conduit or dowel on bottom to form the drainage holes.
• Press the chicken wire into the "mud" and continue to cover form with mix to a depth of 2 1/2 to 3 inches.Check thickness on all sides frequently.
• After the container has set up for several hours, remove the conduit from the drainage holes
• When the container has dried for about 3 days remove it from the form.
• Allow to cure outdoors in a shaded area for about 2 months before filling