Even if you use strictly native plants in your desert garden, you will still need to water them regularly while they become established. Frequently (with cacti and succulents being possible exceptions) you will also need to give them extra water in the hottest months so that they look their best and/or bloom for the pollinators.
In the U.S., as much as 70% of our residential water use goes to landscaping. This is a waste of resources, because this water is treated thoroughly in water treatment plants to get it to drinking water quality. We’re pouring thousands of gallons of drinking water on our plants, which is not ideal. There are a couple of ways to mitigate this waste.
For one thing, not all of your landscaping water needs to come from our water treatment plants. Here are some other sources of water for your plants.
Sustainable water sources for desert gardens
Greywater: This is water from your clothes washer, tub, and bathroom sink that you can redirect to your garden. Usually this is done using a small pump and some pipes and valves. In Tucson, Watershed Management Group has great classes on how to DIY simple greywater systems. Note that you should not use kitchen sink/dishwasher water for this, since it contains too many bacteria due to the food particles. It should go without saying that toilet water cannot be used for this either.
Rainwater: Rainwater that falls on your roof can be directed into basins dug into your garden (passive) or into tanks (active). One of the best resources for DIY rainwater harvesting is Brad Lancaster’s two-volume series of books: Rainwater Harvesting for Drylands and Beyond. You can buy these on Amazon or directly from Brad’s site which also has a lot of great resources on rainwater harvesting. Brad is a Tucson native, and has decades of experience in water harvesting in desert environments.
Reclaimed water: In Tucson, the City of Tucson has a purple pipe system that provides reclaimed water to certain neighborhoods. Watering garden landscapes is a great application for reclaimed water. For Tucson natives, check out the City’s site and contact them for more information. For other desert dwellers, you can check in your city or other locality to see if this option is available to you.
Air conditioner condensate: In the summer, the condensate from your air conditioner can be piped down to water plants. This distilled water is great for plants, particularly in our alkaline soil. All it takes is to direct the condensate down one of your roof spigots and into a planting area. You can also collect it into your rainwater collection tank, if you have one.
Efficient water delivery systems for desert gardens
In addition, even if you use treated water to irrigate your garden there are ways to use it more efficiently. Avoid sprinkler systems or anything that sprays water in the air. You will lose a huge amount of water to evaporation. The most efficient systems are ones that deliver the water close to the root zone.
Drip Irrigation: The best system for desert gardens is drip irrigation. It directs water to the soil with a minimum of evaporative loss, unlike sprinkler systems. It can be fairly easy to DIY, and I will have articles in the future to help gardeners install and maintain basic irrigation systems in their garden. You can also hire landscaping companies or gardeners to install systems for you. You can have systems above ground (which I personally prefer) or ones that are buried.
Soaker hoses: These are a good way of watering plants in the desert. I have buried mine under a couple of inches to ensure that the water wets the soil and roots without having any pooling water, which you can sometimes get even with drip irrigation. The down side is they can get clogged with our mineral-rich water. Just make sure you’re checking their effectiveness a couple of times a year.
Ollas: These are unglazed ceramic clay pots with removable lids that can be buried in the ground (or in planters) and hand-filled every few days with hose water. The water inside the olla passes through the clay wall and out into the soil. This provides plants with a steady supply of water as they need it, with no risk of over-watering. Ollas are frequently imported from Mexico. I recommend looking for them locally, rather than online, since the ones available online are usually significantly upcharged. In Tucson, Acme Sand & Gravel has had them at a reasonable price.
