Subbing out lawns for drought-tolerant landscapes may be a long-term solution to coping with water shortages. But what if you want to keep what you’ve got?
Several readers have expressed urgent concerns: How will their trees and shrubs survive this drought?
“Everyone talks about not watering the lawn, but what about the trees?” said Judith Day of Sacramento. “I have two large shade trees in my lawn, one of which is 60 years old. If I don’t water the lawn, won’t they die? I also have evergreen shade trees within beds, and they are turning brown.
“Years ago, I lost two large shade trees because I didn’t water them in the summer. … Does the city want us to let our trees die?” Day said.
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No, Sacramento likes its “City of Trees” reputation. Deep-water the trees with infrequent soaking. Instead of turning on the sprinklers and watering the whole lawn or flower bed, move a hose around to each tree. (A soaker hose also works.)
Big trees can get by on deep irrigation twice a month or less. Just make sure the water soaks down into the soil; check the dampness with a soil probe or a long, thin screwdriver. Also, use mulch around the evergreen shade trees to help keep their roots comfortable.
“I live in the San Juan Water District,” said David Newland of Granite Bay. “We have been told to stop all outside watering. I have complied, but am concerned about this impact on my plants. I expect the lawn, annuals and some perennials will be lost. I would hope that I can save our 30-year-old camellias and azaleas. Also the Japanese maples and other ornamental shrubs may be lost.”
Linda Johnson, another San Juan Water District customer, expressed similar worries. “We have camellias that are about 50 years old,” she said. “Should the plants be pruned severely? Are there particular mulches that would be more suitable than others?”
Those decades-old camellias got that way because they are naturally drought-tolerant. These examples already have survived severe conditions and still lived to bloom some more.
If given a little shade and good drainage, camellias can be a perfect low-water shrub for the Sacramento climate. Once established, camellias can live on infrequent deep watering, such as twice a month. In fact, they hate soggy conditions.
Sasanqua camellias, the early blooming Christmas varieties, can get by on almost no additional irrigation most winter months. (This winter, they did need the occasional drink.)
Camellias have relatively shallow roots, but deep watering encourages them to grow farther down. That’s an important part of drought resistance. Deep roots can gather more moisture and withstand dry conditions.
Like many shrubs, camellias benefit from mulch, preferably shredded bark. It keeps the ground cool in summer while maintaining moisture. Because camellias are an acid-loving shrub, they like pine needles (another mulch idea), redwood or cedar bark or small wood chips.
Camellias need little, if any, pruning any year. That includes now. Pruning stresses shrubs and trees, and drought causes enough stress without adding this burden to your plants’ life. Also, pruning spurs rapid new growth, which takes more water.
Contrary to reputation, roses also do very well during times of low water. The UC Davis Arboretum irrigates its roses only twice a month, sometimes less. During trials, four rose varieties did so well, they became low-water Arboretum All-Stars: Pink Gruss an Aachen, Mutabilis, Iceberg and Perle d’Or.
Azaleas can be more problematic. “Encore” azaleas – patented new varieties – were developed specifically to be heat- and drought-tolerant. But most varieties will get by just fine with weekly deep watering and mulch. Deciduous native azaleas need less water than most evergreen hybrids. Again, don’t prune azaleas; that’s extra stress.
Hydrangeas – which love a lot of water – will wilt if not irrigated; their big leaves lose a lot of moisture, especially during summer heat. If they droop too much, give them a drink. But it won’t be more than once a week.
Like camellias, Japanese maples become drought-tolerant once established. (“Established” means in the ground and growing, usually a year or more.) Deep roots keep the tree hydrated during dry spells. Irrigate deeply twice a month. Mulch helps; make sure it doesn’t mound around the trunk. That can lead to crown rot.
During drought conditions, perennials may die back or not even emerge. Give them time. When the rains return, so will the perennials. But you may be surprised how hardy Shasta daisies, asters and bearded irises can be with only occasional irrigation.
Some shrubs and perennials may be irrigated with “gray water,” such as leftover (but cooled) cooking water or dish water. If using dish water, use pure soaps (not grease-cutting detergents) and remember, some plants are soap-sensitive. Choose phosphate-free detergents and household cleaners. (Phosphates can kill grevillias, for example.)
In addition, azaleas, camellias and rhododendrons are pH sensitive, so avoid alkaline detergents.
As for the lawn, it should survive, too. According to University of Illinois research, turfgrass crowns will stay healthy with .3 inches of water every three weeks in summer – about 200 gallons per 1,000 square feet.
Most Sacramento lawns normally get 2 inches a week of summer irrigation, or about 1,200 gallons per 1,000 square feet. The difference over a three-month period is huge; 800 gallons versus 14,400.
The grass will turn brown, but (if the crowns stay healthy) the lawn will bounce back into thick green turf – once our weather returns to normal.