Hypertufa Trough Recipe:
1 part Portland cement (no substitutes, e.g., do not use quick drying concrete)
1 part peat moss
2 parts perlite
(We used a 1-gallon plastic pot as our standard of measurement, but you can use anything so long as the proportions stay the same. Wear a mask to filter out the fine particles from the cement.) We used a wheelbarrow to mix the ingredients and found that if the light stuff—the peat and perlite—are added first to the wheelbarrow and the cement—the heaviest ingredient—is added last, it is easier to mix. Add water and stir until it has the texture of thick cottage cheese. It needs to be moist enough to hold together but dry enough to create the sides of the trough without slumping. At this point, you can add concrete color agents if you so choose; we left ours the natural gray concrete color because it looks more like basalt, a northwest rock.
To make three larger troughs (approximately 2.5 feet by 1.5 feet with 8 inch walls), we used two bags of cement, most of one large bag of peat and most of one large bag of perlite. We had enough left over to cover a small rock to make another small trough.
Cover with plastic to help the troughs dry more slowly and allow to dry for 5-7 days before removing from the form, at which time you can roughen up the edges and exterior to make it look more organic. Kym did wonders for the "aging" of her trough when she used that fork side of a hammer to gouge indentations and hack away smooth edges. If the walls are thick, you don't have to be too gentle. When you have it looking like you want it, let it set another week before planting. The longer concrete sets up, the harder it becomes. The final thing I did before planting the trough was to rinse it with white vinegar, (it neutralizes the lime in the concrete). Rinse well. I used a mixture of cactus soil mix and regular potting soil (about a 2/3 to 1/3 ratio).
For my shade trough I planted (clockwise from the upper right) Hosta 'Green Eyes'; Pinellia cordata, a Jack-in-the-pulpit relative; Aspienium trichonomanes (Maidenhair Spleenwort); Disporum sessile 'Goldbug'; Terra Nova Nurseries’ Ajuga 'Sparkler'; Hackenochloa 'Sunny Delight'; Hosta 'Mouse Ears'; Aspidistra elatior 'Asahi', commonly called Cast Iron Plant, from Cistus Nursery; and Selanginella braunil, a moss-relative that is supposed to turn a pinkish-orange in winter. The Pinellia, Disporum and Selanginella are from Edelweiss Perennials. I bought the Aspienium and 'Sunny Delight' from Out in the Garden Nursery.
I can't wait to see what Kym does with her troughs! If you have photos of a trough you've created, we’d love to see it. Some of the most wonderful troughs I've seen are in the Iseli Nursery display gardens (middle photos). And these cute troughs are for sale at Bauman Farm & Garden, bottom photo.
Fine Gardening also offers trough-making instructions and photos, which you may fine helpful.