When my friend Jonathan Long bought a house, part of its side yard was too steep to plant easily or efficiently. Being a practical man, he decided to terrace the slope.
It's a solution that makes sense for anyone wanting a better vegetable bed on a sloping lot.
A terrace's stone walls absorb heat during the day and radiate it back later, warming both the air and the root zones of plants. Depending on the dimensions of the bed and the thickness of the stone walls, that might mean warmer soil earlier and later, and a longer growing season. An added bonus is that cold air slides off and down terraces rather than settling around plants where it can damage them.
If your site is south- or southwest-facing, so much the better, especially for heat-loving crops like tomatoes, peppers, eggplant, potatoes, tomatillo and ground cherries.
Jonathan started by cutting the sod, turning it upside down and covering it with soil. The overturned grass and weeds became humus for the soil. Then he cut into the slope to form four equal-size beds that step down to street level.
Next, he dry-stacked stones (available from rock yards or quarries) at the lower front edge and ends of each terrace to make a broad "U." Each terrace wall, none more than 20 inches high, is stacked to lean in slightly toward the dirt it holds back. This helps stabilize the wall. The higher the wall, the more potentially unstable it is, so he kept his low.
With the hard work done, Jonathan set pieces of broken concrete on the soil at the back of each terrace, forming pathways from which he can plant, weed, harvest and water.
If you're inspired to build a dry-stack wall for your own terraced vegetable beds, here are other considerations:
• Plant crops that don't require a lot of digging, such as root crops.
Spadework will be awkward unless you stand on the soil in the bed, and you want to keep this to a minimum because it compresses soil and endangers your dry-stack wall. Likewise, avoid planting corn and other large plants because harvest will be near impossible in such a confined space.
• Dry-stacked walls can be dismantled and moved or modified as needed. A cement foundation or adding mortar between the stones would increase the stability of the wall.
• Terraced beds are more vulnerable to erosion than a flat garden. Water, if applied too quickly, doesn't have far to go until it runs over the edge of or through terrace walls. Add lots of organic material to soil to hold in moisture.
• The best way to water terraced beds is with soaker hoses or drip irrigation on a timer. Your plants will be happier, healthier and more productive, and you'll save time and money on water, too.
• Stone walls provide lots of pockets and spaces for planting small herbs like creeping thyme or for sweet treats like alpine strawberries. (Don't plant alpine strawberries into a south-facing wall; it's too hot. They'll do better along an east-facing edge, at the wall's bottom edge or at the top where wall meets soil.)
• Stone walls may shelter slugs and garter snakes. Slugs can be controlled with beer traps, regular nighttime patrols with scissors, or with organic bait. Snakes are always welcome in my garden, though I've been known to jump straight up when one slithers out.
- Vern Nelson
If you want to automatically receive a daily homes and gardens tip, sign up here.