Summer hasn’t arrived yet, but Sonoma county is already officially in a drought emergency, following declarations from county and state leaders over the last few weeks. That means we need to think about water conservation more than ever, including in the garden.
There’s a difference between a drought and the dry season. We have a dry season every year here in our Mediterranean climate, usually from June to October. A drought occurs when we don’t get enough rain during the entire rainfall year.
A rainfall year is not counted by the calendar but instead from October to September, from the beginning of the rainy season in one year to the end of the dry season the following year. The historical average annual rainfall in Santa Rosa is 33.89 inches. In 2020’s rainfall year, we got only 18.13 inches. So far this rainfall year, only 12.41 inches of rain have been recorded, about a third of normal.
So what can we do to make the most out of every precious drop in our gardens?
Xeriscaping — planting a garden of drought-tolerant ornamentals that require little to no summer irrigation —is one solution, but only if you already have planted it. Even drought-tolerant or low-water-use plants need a period of time with irrigation to grow deep roots. The challenge for most homeowners now is how keeping their non-drought-tolerant garden plantings alive using as little water as possible.
As those who pay their water bills know, water isn’t cheap. And now it’s also getting scarce. So, let’s think about ways to keep the landscape and home gardens healthy while conserving water.
First, don’t over-water. The rule of thumb is that plants need about an inch of water a week. Here, where summertime temperatures can get very hot, you can make that a generous inch, but over-watering is wasting water. Sopping-wet soil is also prone to rot and mildew. And over-watering can cut the oxygen in the soil, which plant roots need to thrive.
To make the most out of every drop of water you use, think “slow.” Don’t flood an area or sprinkle the soil rapidly. You want the water to percolate down into the soil rather than flow off the surface into other areas.
By nature, plants have their feeder roots in the richest soil, which is usually the topsoil layer near the surface. The deeper roots are looking for moisture. Sprinkling the soil quickly encourages weak root systems to cluster near the surface but doesn’t force the plant to dig deeply for water.
If you use sprinklers or drip irrigation, curb the flow but increase the length of time you allow the water to run. That way you can water less often but more effectively use less water. It sounds counterintuitive, but it’s not.
If you have irrigation that sprays water across swaths of lawn or gardens, set empty tuna cans or small dishes around the area being covered and see how long it takes for your irrigation system or sprinklers to fill those cans a half-inch deep. Irrigate twice a week for that amount of time each session and you’ll be giving your plants an inch a week. Be stingy. Don’t over-water.
Water in the morning
The best time to water is the morning. This gives the plants time to dry off before the night returns. Our cool nights with fog are fabulous for sleeping but can encourage mildew. Watering during the heat of the day means the heat and sun can evaporate much of the water before it gets down to the plant roots.
Let everyone in your household know they should save water. Keep a plastic bucket near each sink and shower in the house. Rather than let the water run down the drain, keep it in the bucket until it’s full and use it to water indoor and outdoor plants in pots and containers. If your washing machine’s gray water is piped outside and spills down a slope, divert it into a container with a lid and use it to water selected trees and shrubs.
Consider switching your irrigation system to a soil moisture-based control system. We now have technology that automatically measures the amount of moisture in the soil and tailors the irrigation schedule to use the minimum water most effectively. These systems usually cost $200 to $300, but they may pay for themselves quickly if your water bills are high.
There are also inexpensive soil moisture measuring devices that can tell you the level of soil moisture in the garden. You just shove them point first into the ground and they give you a moisture readout. They cost about $10 each but can give you a heads-up to prevent over-watering.
If you haven’t checked your irrigation system in a while, inspect the areas where it’s delivering water. You may have noticed instances where people are irrigating sidewalks and streets, or water is running off lawns and down into a gutter. That’s inexcusable during a serious drought. Adjust your irrigation equipment so water lands only on lawn or garden soil.
Use micro-irrigation whenever possible. These slender tubes, connected to your main irrigation lines, deliver water to selected trees and shrubs and keep them happy without wasting a drop.
There are many irrigation specialists in our region. Just look online to find them. What they charge to do the irrigation properly can save you money in the long run. And you get professional service.
A drought year is not the time to plant a new garden or re-landscape. But if you’re determined to plant or refurbish garden areas this spring, think about irrigation zones.
Plants with similar water needs should be planted together. Each zone represents a specific sun or shade condition which defines the kind of plants in the zone and the appropriate sprinkler or irrigation strategy for that zone.
Prioritize the plants that mean the most to you. This is the time to be ruthless. If you have plants that are water hogs and that you are lukewarm about, you may need to let them go. Direct your precious water resources to the things you care about the most or would be the most difficult to replace. Maybe your vegetable garden wins out because of the food it provides. Ask hard questions. Does it provide shade? Does it offer habitat for birds and insects?
The Environmental Protection Agency has published an excellent booklet on how to conserve water in your landscape. You can download a copy for free at bit.ly/3noMNRz.
Another resource, specifically for Californians, is “Beyond Drought-Tolerant” by the people at Sustainable Conservation. It’s a low-water gardening guide full of good ideas and recommendations. You can download a free copy at suscon.org/landing/landing001.html.
Finally, be of good cheer. If your cherished plants have to struggle this summer, well, so did we all during the last year. Just make every drop of water count to get them through the season — and hope for more rain.