Trough gardens are an attractive way to display a variety of alpine plants, and these gardens can be part of your outdoor landscape all year-round. We’ll show you how to not only plant the garden but make the stone-like trough container as well.
Making the Trough
(available at home and garden centers)
1 part sphagnum peat moss
1 part perlite (a natural volcanic glass)
1 part dry cement, dyed
1 part engineered fiber for reinforcing concrete (fiberglass or spun glass)
- Mix all ingredients (figure A) together and add water until the mixture becomes the consistency of oatmeal.
- Make a trough mold using a plastic dishpan or litter pan; the shape and depth of the trough can vary and is up to you. Line the pan with plastic, making sure the plastic goes over the edges of the pan (figure B). This will help release the finished trough from the mold pan.
- Put the mixture in the trough mold and begin to build up the edges, then the bottom of the trough.
- Fold the plastic over the sides and let the formed trough set until the bottom no longer “gives” (figure C). This step could take anywhere from two to four days.
- When the trough has set sufficiently, peel back the plastic and gently remove the new container from the mold.
- Add texture to your trough by roughing up the sides with a wire brush. If the reinforcing fibers are visible, use a propane torch to melt them off.
- Use a keyhole saw to add drainage holes in bottom (figure D). Before planting, cover the drainage holes with landscape fabric to prevent soil from washing out (you can also use a paper coffee filter).
- Allow the trough to cure completely for one to three weeks.
Planting the Trough
1 part topsoil
2 parts play sand
plants of your choice
- Mound soil in the trough and press gently.
- Place medium-size moss rocks on top of the soil (figure E) to add a mountainous alpine feel to the trough garden.
- Insert alpine plants into planting holes. Some good choices: dwarfed blue fescue, creeping phlox (to cascade over the edge), penstemon.
- Add a layer of crushed granite mulch around the plants. This enhances the appearance and helps hold soil in place.
- Water weekly during the summer, less often in winter.