A California native who lives in arid San Diego, Nan Sterman has grown up gardening with little water. Her stylish design boasts three levels that lead to a slab stone bench tucked beneath an espaliered fig. To grow food where there is little water, Nan relies on drought-tolerant edible plants — figs, artichokes, and herbs — combined with an efficient drip irrigation system.
Each year, rains fall in San Diego from November through March. Then it’s hot and dry until the following autumn. To avoid wasting water, Nan concentrates on plants that are adapted to her dry climate, rather than growing plants native to wetter regions that would require regular and frequent irrigation. “My philosophy is that if we are going to spend water, let’s spend it on something that feeds us, but we should still use as little water as possible,” she says.
Nan has designed a beautiful, productive garden in which to grow low-water-use edibles managed with water-wise techniques like mulching and smart irrigation. The plot measures approximately 24 feet long by 20 feet wide and gently slopes uphill. She divided the garden into three terraced levels, with the entry at the lowest point. “Each level is a single step above the lower one, and the central path terminates at a slab stone bench beneath an espaliered fig,” explains Nan. The terraces add visual interest to the garden, but they don’t affect the water-wise aspect. Nan recommends using a light-colored, stabilized decomposed granite for the pathway and upper landing. Install aluminum edging to keep the material in place and out of the beds. (Sure-loc makes a good aluminum edging.) “Set it flush to the surface of the walkway so that it is basically invisible,” she advises.
Water-wise pots. Two large, blood red ceramic pots (22 inches wide and 27 inches tall) surrounded by white-flowering yarrow flank the entrance to the garden, with each containing a multi-trunk bay laurel. Nan suggests choosing bay trees that are about 31/2 feet tall. They’re underplanted with dittany of Crete, an ornamental variety of oregano with fuzzy, silvery leaves and large pinkish flower bracts. She notes that the oregano cascades beautifully over the sides of pots. Pots are topped with 3/8-inch rounded gravel. To keep the plants watered, each pot contains a cylinder of DriWater, which holds a water-retaining gel composed of common food-grade ingredients. The DriWater helps keep the plants moist over a period of time without additional watering, and the cylinders only need to be replaced approximately every three months or so, depending on the season and weather.
Nan has divided her garden into two water zones based on her plants’ needs (see diagram on next page). Zone H1 has subsurface drips (placed 4 to 6 inches below the surface), and zone H2 has on-surface drips. Both are covered in mulch, and she recommends using an inline dripper line (such as Techline CV available from Netafim), with drippers spaced every 12 inches. The lines are best set 12 inches apart in parallel lines.
Select a drip rate appropriate to your soil type. For plants in heavy clay soil, choose a slower drip rate such as 0.26 gallons per hour (GPH). Plants in well-draining sandy soils do better with a drip rate of 0.6 GPH, while plants in loamy soils that hold water, yet drain well, do best with a drip rate of 0.4 GPH. For plants in the coarsest soils, try a drip line that delivers water at 0.9 GPH.
Nan’s irrigation zones
Mediterranean diet. There isn’t a wide selection of water-wise edibles, which Nan says often surprises people. She points out that most water-wise edibles originate from Mediterranean climates, where rainfall is extremely limited. This multitiered garden includes figs and grapes, as well as artichokes. Oregano, lemongrass, thyme, rosemary, and peppermint geraniums provide seasonings and fragrance. In the oregano beds, flagstone stepping stones lead to the grapevines, allowing easy access for maintenance and harvesting. Each plant was carefully selected by Nan for its drought tolerance, and once established, needs very little water. “Yarrow, for example is native across the Northern Hemisphere, including California — where it is extremely drought tolerant,” she says. “Only the lemongrass is on the thirsty side, but I find it gets along just fine with far less water than its Asian heritage would suggest.”
Smart irrigation technology. Because water-wise gardening involves more than just picking the most drought-tolerant plants, Nan also relies on smart infrastructure. “Irrigation technology and irrigation management are just as important as a good layer of mulch,” she remarks. “Drip irrigation puts water into the soil where the roots live, and as each drop is released, it is absorbed directly into the ground,” Nan explains, noting that the efficiency rate is 90 percent or higher. She prefers drip irrigation to overhead spray systems, which spray water into the air, wasting 50 percent to evaporation or misdirection. In-line drip, also called dripperline, is hands-down the most efficient of irrigation technologies” Dripperline is 1/4- or 1/2-inch-diameter polyethylene tubes with water emitters embedded inside the tubes; when the emitter releases water, it drips out the holes.
Once the irrigation lines are in place, the planting beds are topped with a 3-inch layer of mulch over the dripperline, further reducing water loss. “The need to irrigate [above and beyond the water delivered by the drip system] goes down to almost zero,” she says. “This garden needs little to no fertilizer, and only the grapes and fig require pruning.”
‘Panache’ fig. The espaliered fig forms the back “wall” of Nan’s garden. She advises pruning it to a broad espalier about 6 feet wide and 18 inches deep (front to back), training it into a wide and multi-trunked tree. This variety produces figs with green and yellow stripes. “The flesh is strawberry red and very sweet,” adds Nan. (Zones 6 to 11)
Grape. The grapevines will form the side “walls” of the garden and are trained on two horizontal cordons. Nan advises checking with your local Cooperative Extension Service for variety suggestions because grapes are highly region-specific. She adds that there are four types of grapes (wine, juice, fresh-eating, and raisin) to choose from, and many colors of fruits (red, gold, green, white, and purple) within those groups.
‘Violetta’ artichoke. In Nan’s region, artichokes are a perennial plant, but in colder regions, they are grown as annuals. “ ‘Violetta’ is an Italian heirloom variety with purple blush buds,” she says. “The buds are harvested starting when they are ping-pong-size all the way up to softball-size.” (Zones 7 to 11)
Bay. Planted in tall ceramic pots at the garden entrance, bay adds a note of formality to this garden plan. It is an evergreen Mediterranean tree with a slightly conical shape and aromatic glossy green leaves. It adds flavor to pasta sauces, soups, and other dishes. (Zones 8 to 11)
Dittany of Crete oregano. This tender perennial is tucked at the feet of the bay laurel trees so it will spill over the edges of the large pots. The silvery green, velvety leaves invite touch as one enters the garden, while attractive pink flower bracts attract beneficial and pollinating insects. (Zones 7 to 11)
Dwarf or ‘Dwarf Greek’ oregano. These low-growing oreganos quickly form a carpet of deep green foliage, brightened by white or purple flowers. ‘Dwarf Greek’ has a more pronounced flavor, if you’re looking to use this in cooking. Nan advises starting with plants in 4-inch pots. (Zones 5 to 11)
‘Tuscan Blue’ rosemary. Rosemary is beloved for its extremely aromatic needlelike foliage and flowers, typically soft or deep blue, but sometimes white or pink. “To form the front and rear ‘walls’ of the garden, lightly prune the rosemary to 3 or 4 feet tall by 4 feet wide,” says Nan. Generously sprinkle homegrown rosemary over roasted potatoes or homemade focaccia. (Zones 8 to 11)
Lemongrass. Easy to grow, lemongrass forms attractive grassy clumps with pale green leaves that smell of fresh lemons. Use the white stalks in Asian dishes, and steep the green parts in boiled water for tea. (Zones 8 to 11)
Common (English) thyme. Nan designed water-wise thyme under and around the stone bench so it can release its fragrance when stepped on. Thyme also edges the top tier of the garden, tumbling over the stone wall. The spreading plants grow to be about 1 foot tall and produce tiny pink flowers. (Zones 5 to 11)
Peppermint-scented geranium. There are so many reasons to love this plant: it has soft fuzzy leaves, a minty aroma, and delicate white and pink flowers, plus it’s easy to maintain. Peppermint geranium grows to be 2 feet tall and 4 feet wide at maturity. Nan used it at the base of the rosemary and fig, so people sitting on the bench brush against the leaves and release the delightful aroma. (Zones 10 to 11)
‘Otto Quast’ Spanish lavender. Planted as a low hedge at the base of the grape vines, ‘Otto Quast’ Spanish lavender is a low-maintenance perennial with showy deep purple flower spikes that attract pollinators and butterflies. (Zones 7 to 9)
Yarrow. A hardy perennial that tolerates drought, yarrow has ferny foliage and flat-topped flowers that are extremely effective at attracting beneficial insects. Nan chose a white-flowering variety to ring the base of each potted bay tree. (Zones 3 to 11)
1. ‘Panache’ fig
2. Grape
3. ‘Violetta’ artichoke
4. Bay and dittany of Crete oregano
5. Yarrow
6. Dwarf or ‘Dwarf Greek’ oregano
7. ‘Tuscan Blue’ rosemary
8. Lemongrass
9. Common (English) thyme
10. Peppermint-scented geranium
11. ‘Otto Quast’ Spanish lavender