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Trough Gardening |
By Stan Barrett, Colorado State University Cooperative Extension Master Gardener, Denver County
If you thought there were no new gardening ideas under the sun, you likely haven't been introduced to trough gardening.
It's a concept that became popular in Britain at the turn of the century when horse troughs were replaced with metal tubs, thus leaving a lot of rectangular stone containers around the landscape.
Creative gardeners saw the potential for using these troughs to grow miniature gardens. Owners of country homes used a collection of planted troughs to define boundaries of vegetable gardens. Now, they are sought after by container gardeners for growing alpines and other small plants.
A technique for making artificial stone troughs was developed in the 1980s. It uses "hypertufa," a mixture of Portland cement, sphagnum peat moss and perlite, reinforced with chicken wire.
Building a hypertufa trough
Two nested cardboard boxes provide a form; the space between the boxes contains the hypertufa.
- Select two stout cardboard boxes for the form. Suggested sizes are 12" x 16" for the outer box and 9" x 13" for the inner box, leaving an all-around gap of about an inch-and-a-half. Thedepth of the inner box defines the depth of the finished trough --five inches is a good depth for most small plants. Cut the outer box to 6 1/2 inches deep.
- Mix the hypertufa, using two parts cement to three parts peat moss and three parts perlite. Gradually add enough water to achieve the consistency of mayonnaise.
- Trowel a one-inch layer into the bottom of the outer box.
- Cut a piece of one-half inch chicken wire to a rectangle of 11" x 15." Push it just below the surface. Add mix to bring the thickness up to one-and-one-half inches.
- Create drainage holes by pushing five evenly spaced one-half inch dowels, four inches long, through the chicken wire.
- Fit the inner box, bottom up, into the outer box leaving equal spaces on all sides. Push the box one-fourth inch into the mix.
- Cut a strip of chicken wire 5" x 50." Bend to fit loosely around the inner box. Twist the wire ends together to make a firm joint at the middle of a long side. Push the wire one-fourth inch into the mix.
- Carefully fill the space with the mix, packing it in place with a paint stick. Fill both sides of the chicken wire to the top edge of the inner box.
- Allow 10 days to harden. After three days, cut away the outer box. After another week, remove the inner box and the dowels.
Finally, to reduce the surface alkalinity, hose down the trough twice a day for a week. Your trough is now ready for planting.
Planting your trough garden
If you build a small trough, such as suggested above, you'll find obvious limits as to what can be planted. To maintain a pleasing scale, consider only small plants. This likely will mean using sun-loving plants because shade-tolerant plants generally are those with larger leaves.
You can chose annuals, herbaceous perennials and alpines. Combining annuals and perennials works well, but mixing in alpines generally does not work well because they usually have very specific water and drainage requirements and therefore need different soil. Remember, your trough garden will need to be watered and fertilized more frequently year-round than an in-ground garden. They also may need protection during the winter, such as mulching with weeds or straw.
If you choose annuals, you'll enjoy a long summer bloom season and by-pass any worries about wintering over. Perennials are available in greater variety than annuals and often feature more interesting foliage when they aren't flowering. You usually can divide them in a year or two, to obtain more stock. Choose hardy varieties so they will overwinter without a lot of care.
To prepare the trough for planting, cover the drainage holes with pieces of fiberglass mesh, such as is used for window screens. Follow this with a one-half-inch layer of pea gravel. Fill with an all-purpose mixture of commercial potting soil, peat moss and sharp sand or perlite, all in equal volumes.
Plant combinations of the following plants that have similar soil, light and moisture requirements.
Annuals
- Scarlet verbena (`Derby' - 10" tall) with dusty miller (`Silver Dust,' - 8" high) and deep blue trailing lobelia, that will grow to about four inches high.
- Heliotrope (`Marine,' 15" tall) with sweet alyssium, anypink variety that will grow about four inches high.
- Livingstone daisy (Mesembryanthemum, 2 yellow or pink, six inches high) with deep blue and white trailing lobelia that will grow to about four inches.
Perennials
- A fragrant herb trough using rosemary (`Corsican prostrate, to 12 inches tall) with sage (Salvia Officinalis `Tricolor,' clipped to 10 inches) and lemon thyme that will grow to four inches high.
- Miniature roses (`Starina,' red/orange, 14 inches tall) with pale blue Veronica (`Bird's Eye,' two inches high).
- Daylily `Stella D'Oro,' 12" with cinquefoil (Potentilla Atrosanguinea, `Gibson's scarlet, 8 inches).
Photograph courtesy of Judy Sedbrook.
