Water use in dry climate gardens

Water is life.

I garden in the arid southwest US, and soaring summer temperatures can dry things out fast. Water conservation is key to thriving gardens here and every tool is needed. I'll share methods I've used and am sharing a couple of great reference books on gardening in drylands.

The main practices I use are to slow evaporation with mulch and shade. I also look for the most climate adapted crops and varieties, and I liberally apply compost to build organic matter in the soil. I start seeds indoors which requires less water than starting outdoors.

One benefit of biointensive gardening is that by using close spacing, I don't have to water large areas and the plants fill in to shade each other. Each practice helps, but stacking and overlapping multiple practices supercharges the results. If I added a little more water storage, I could almost see growing much of my garden with the rainwater I collect.

For further reading:

Growing Food in a Hotter, Drier Land

Lessons from Desert Farmers on Adapting to Climate Uncertainty

by Gary Paul Nabhan

Gardening with Less Water

Low-Tech, Low-Cost Techniques; Use up to 90% Less Water in Your Garden

By David A. Bainbridge

Keeping gardens cool

Shade

While summers have never been cool here, we are now regularly setting heat records. My garden suffers in the heat and I dread even simple tasks outside of early morning. Tomatoes no longer set fruit at higher temperatures, even when they have plenty of water.

One easy solution is shade. Tender plants may grow fine in the shade of walls or under nurse trees. For my bigger beds though, shade cloth is the best product. It should let through some light but provide enough shade to cool things down and reduce sunscald. I use 30-50% shade cloth and staple or clip it onto posts or frames around my beds. For those tomatoes, I get better fruit set and even less pest pressure.

Keeping water in the dry garden

Mulch

Mulch is a valuable layer between the garden roots and the blazing sun. With deep mulch, water will be less likely to evaporate from soil. I prefer to mulch with shredded leaves and the dry material from my cover crops, but I also hoard chipped wood and newspaper for mulch. Newspaper and thick paper mulch can also reduce weed pressure if spread thickly and covered with other materials.

Soil Organic Matter

If I were to pick one indicator of garden success, I'd pick soil organic matter. It's a winner for lots of different reasons, but water holding capacity is the one that tops them all. Dark soil that's rich in organic matter holds moisture longer than sand and with better aeration than clay. Here in the desert, building soil organic matter is a priority.

I grow green manures and cover crops in my garden, as well as composting. To me, those living roots build beds faster than compost & with less effort. For every 3 growing seasons, I try to have a cover crop in every bed at least once. I use tillage radish for compacted soils, but always with at least 1 legume and one grass. For fall I like radish, vetch and rye. For spring, I like field peas and oats. In summer I use buckwheat, but am looking to try others this summer.

Compost Production & Use

Composting is easy to do using all the garden, landscape and kitchen waste. I also save neighborhood leaves to add and add cover crop biomass to my compost pile. I could never raise the soil organic matter with what I make, but I can supplement the garden fertility and increase the water holding capacity of the soil.