With the drought on everyone's mind, a talk on "Water Wise Gardening" drew a sizable crowd to an Atherton Earth Day event in Holbrook-Palmer Park on April 21.
Julie Montanari, a master gardener and landscape designer from San Mateo, told the gathering of about 60 people that the worst outdoor residential water wasters are pools and lawns.
She recommended homeowners, at a minimum, follow the guidelines in California's 2010 Water Efficient Landscape Ordinance. The law sets minimum regulations on landscape water use for cities and towns, she said.
The most important guidelines in the law, Ms. Montanari said, are:
● Start with a water budget, a limit on how much water will be used (which local officials are threatening to impose) and design landscape to fit that budget.
● Limit or eliminate lawns and pools.
● Use water-wise plants.
● Use drip irrigation, efficient sprinkler heads and "smart" irrigation controllers that change watering patterns with weather changes.
● Make sure all water that goes on a property (rain and irrigation) stays there, with no waste.
● Use mulch.
● Group plants by their water needs.
Use at least 50 percent low-water plants
The guidelines say that no more than 25 percent of plants in a garden should be in high-water plants, which include lawns, white birch trees and annuals. In the summer such plants need an inch of water every six days, she said.
Moderate-water-using plants, including many shrubs such as roses, hydrangeas and azaleas, need an inch of water every 10 days in the summer, she said. With the high-water-use plants, they should add up to no more than 50 percent of a garden.
At least 50 percent of plantings should be low-water plants, Ms. Montanari said. Those plants include many plants native to California and other Mediterranean climates including most of the Mediterranean coast (southern Europe, Middle East and Northern Africa) and parts of Australia, South Africa and Chile. Some examples are Italian Buckthorn, yarrow, bush anemone, Lantana, sages, wormwood and lavender.
In the state guidelines, fruits and vegetables are allowed additional water.
Over-watering plants is a widespread problem, Ms. Montanari said. "They probably need less than you or your gardeners are giving them," she said.
Ms. Montanari says there are hundreds of water wise plants to choose from, including many that offer colorful flowers and, or foliage. "People tend to be more familiar with traditional thirsty plants, but they don't need to give up on color or interest in their gardens. They just need to use different plants," she said.
The common, thirsty, pink Hydrangea macrophylla (Garden Hydrangea) is an example of a common higher-water-use plant that can be replaced with lower-water-using substitutes with a similar look and feel, Ms. Montanari said. She recommends planting Ribes sanguineum 'Claremont' (native California Flowering Currant), which grows about 5- to 10-feet tall and takes sun or shade; the Lantana hybrids 'Bandana Cherry' (2-feet by 2-feet) or 'Irene' (3-feet by 4-feet), which are best in full sun; or Lagerstroemia 'Pokomoke' (Dwarf Crape Myrtle), 3- to 5-feet tall, and also best in full sun.
To substitute for the common, thirsty, blue/purple Rhododendron, Ms. Montanari recommends Prostanthera ovalifolia 'Variegata' (Australian Mint Bush), 8-feet tall, and best in full sun; Vitex agnus-castus (Chaste Tree), a small tree that likes full sun or Ceanothus 'Dark Star' (California lilac), 5-feet tall and best in full sun.
"These are the kinds of plants we need to see in our gardens," she said.
Wait before you plant
After her talk, Ms. Montanari emphasized that now is not the time to put in new plantings, because even low-water use plants need lots of water until they are established.
"They should turn the water off now, but wait until fall to plant," she said. In the fall, she said, "plants can begin to get their root systems established through their first winter and spring and be in better shape to take on their first hot summer." It takes at least two winters for a new plant to become "established," she said and for a low-water plant to be able to be irrigated at a low level.
Instead of running out to buy and install new plants, Ms. Montanari said, now is a good time to plan the garden, to sheet mulch the existing lawn, to do any hardscape changes such as paths and patios and convert irrigation from spray to drip. "This will take some time," she said. "The planting can then be scheduled for October or November."
Sheet mulching is something that can be done now, and will relieve the resident of having to spend the summer looking at a dead lawn. To sheet mulch put compost, paper or cardboard and lots of mulch right on top of the existing lawn, Ms. Montanari said. "This allows the lawn to compost in place and helps to build healthy soil." By planting time, she said, the soil will be in much better shape.
Ms. Montanari said that in addition, by turning down the irrigation right away, people will be able to see what plants should be removed in the fall. "People often have shrub and flower plantings that are a mix of plants that require a little water and plants that require a lot," she said. "If they turn down the irrigation, some plants will suffer, but many will not." She said plants that perform poorly can be taken out and replaced in the fall with plants that require less water to thrive.
The correct way to "turn down the irrigation" is to reduce the frequency, not the duration, of watering, Ms. Montanari said. Watering for too short a time means water will never get to a plant's roots, she said.
Making changes in an irrigation system can also save a lot of water, Ms. Montanari said. Not using sprinklers is preferred. "We want to move to things that we can water with drip irrigation," she said. Barring that, the spray heads on existing irrigation systems can be changed for more-efficient spray heads.
Mulch, a layer of at least two inches of organic matter put on planting beds, can also conserve water. To start with, she says, don't rake leaves. "They call them leaves because you should leave them," she said. Another source of free mulch is wood chips, which many tree companies will deliver. "Any mulch will keep the water in the soil," she said.
Ms. Montanari urged local residents to "use our limited water to preserve the trees," which can be irreplacable. "If people have any question about the health or water needs of their trees, they should bring in a certified arborist to look at them," she said.
In response to questions about watering redwood and oak trees, Ms. Montanari said that neither should need supplemental water; native oaks because they have evolved to need no summer water and redwoods because "if your redwoods are healthy ... they're probably tapped into ground water."
If you must have lawn
What about those who think they just can't live without a lawn? There are alternatives, she says. One is "no-mow turf" of native California grasses, which grow to be about a foot tall and then flop over. "If you don't mow them, you don't need to water very much," she said. "Dogs love them. Kids love them."
There are also flat, walkable ground covers, incluing Silver Carpet, Elfin Thyme, germander and beach strawberry, Ms. Montanari said. On slopes, try low-growing, sprawling shrubs, she said. In shady areas, native yarrow can be planted as seed and then mowed like a lawn, she said.
Once the lawn is gone, paths will need to be added; she said. "These paths can be a main design feature of the garden."
Low-water-use gardens can also, she said, be in almost any style, including a cottage garden. "Roses aren't too bad," she said, "especially on drip irrigation."
How much difference can taking out a lawn make? In a project Ms. Montanari did in Millbrae, replacing a small front lawn with 15-percent gravel paths, 80-percent low-water shrubs and two Japanese maples, all on drip irrigation, water use went down from an annual 16 CCF (CCF means 100 cubic feet) to 3 CCF, Ms. Montanari said.
The residents also saved on maintenance because instead of weekly attention, the garden now only need quarterly weeding, pruning and irrigation checkups.
Ms. Montanari shared following resources:
Water Use Classification of Landscape Species table:
Local Organizations for help with Water-Wise Landscaping and Native Plants:
Arboretum All-Stars plant list:
Books about Water-Wise Landscaping and California Native Plants
(Most are available from the San Mateo County Library system):
● Sunset Western Garden Book, Kathleen Brenzel, editor
● Plants and Landscapes for Summer-Dry Climates, Nora Harlow
● Reimagining the California Lawn, Carol Bornstein, David Fross, Bart O'Brien, John Evans
● Landscape Plants for California Gardens, Bob Perry
● California Native Plants for the Garden, Carol Bornstein, David Fross, Bart O'Brien
● Growing California Native Plants, Marjorie G. Schmidt
● Designing California Native Gardens, Glenn Keator, Alrie Middlebrook
● The American Meadow Garden, John Greenlee
● Rainwater Harvesting for Drylands, Brad Lancaster
● Designing with Succulents (and other titles), Debra Lee Baldwin
●The Water Wise Home, Mora Allen.
Other books available from the San Mateo County Library System:
● Beth Chatto's gravel garden: drought-resistant planting through the year, Beth Chatto
● Lawn gone: low-maintenance, sustainable, attractive alternatives for your yard, Pam Penick
● California native gardening: a month-by-month guide, Helen Ann Popper
● Waterwise plants for sustainable gardens: 200 drought-tolerant choices for all climates, Lauren Springer Ogden
● Drip irrigation for every landscape and all climates : helping your garden flourish while conserving water: outwit droughts with expert guidance, Robert Kourik
● Life after lawns 8 steps from grass to a waterwise garden, Molly Bogh and Bill Schnetz.
Display Gardens and Garden Tours focused on California Native Plants:
● San Francisco Botanical Garden (formerly Strybing Arboretum)
● Regional Parks Botanic Garden (California Natives)
Native Plant Nurseries:
● Yerba Buena Nursery, Half Moon Bay
● Blue Sky Farms, Half Moon Bay
● Bay Natives, San Francisco
● Las Pilitas Nursery, online.
● San Marcos Growers, online.
Sheet Mulching (Lawn Removal) Instructions:
Resources for Drip Irrigation:
● The Urban Farmer Store, San Francisco
● Foothill College holds classes, Los Altos Hills