As a child growing up in southern Idaho, I understood that water was a valuable commodity. The adults in my life frequently talked about the weather, especially in relation to crops. Too much rainfall could rot the crops; too little left them parched.
Now that I garden on the high plains of Colorado, I have an even greater respect for the value of water. Colorado is considered a semi-arid state. In fact, yucca and paddle cactus grow in the field behind my house. The mountains get their fair share of snow in the winter, but conditions are mild in my neck of the woods.
Because my home’s within the city limits, I pay big bucks for city water, which leaches right through the sandy soil in my yard. A steady wind blows fairly continuously, drying the soil out even further.
No wonder then that a Google search on water conservation practices for vegetable gardens came up with numerous links from the Colorado State University Extension.  Water conservation is a big issue here for just about everybody. Below are a few of the water conservation measures recommended by the university. I’ve already implemented some of these in my own garden and plan to add more this spring.
Plant a Windbreak
Whether you live on a rural homestead or an urban plot, a few strategically placed trees and shrubs can cut down substantially on the amount of wind blowing through your backyard, which will also keep your soil from drying out as quickly. In addition, windbreaks can keep your home and garden cooler in the summer, while also protecting it from fierce winter weather.
On a large homestead, plant several rows of evergreens and deciduous trees at least fifty feet from your home in an L or U shape. Plant trees in the direction of the prevailing winds – on the north or northwest side of your property.
In urban and suburban yards, simply plant a few trees and shrubs in your yard. Just make sure to select drought-tolerant trees and shrubs  adapted to your area. Choose perennials and even lawn grasses based on their ability to tolerate some drought as well.
Improve the Soil
Improving your soil not only increases your harvest, but it can also reduce water use. Sandy soils especially tend to leach water. Dig two to four inches of compost or manure into your garden annually to improve its texture. Peat moss is well-known for its water-holding properties, but it’s rather expensive and is not easily renewed. Use it sparingly when you first prepare your garden beds and make sure you moisten it thoroughly before you dig it into your garden. Dry peat moss actually wicks moisture out of the soil.
Plant a cover crop during the fall and winter months, and dig it into the soil in the spring. Cover crops add nitrogen to the soil, improve the soil’s texture, and reduce soil erosion during the winter.
Over the years, I’ve probably tried just about every type of mulch on the market in my garden, and they all help conserve moisture. They also reduce weed growth and can keep the soil warmer. My favorite mulch for the vegetable garden is plain old untreated grass clippings. After mowing, I spread the clippings over my garden soil every week in a one-inch layer. (Thicker layers tend to rot and turn smelly.) I love grass clippings because they’re free, they break down quickly, and they add nitrogen to the soil.
I’ve also tried black plastic mulch stretched over the soil. I’ve seen this approach touted by many extension offices and I know several commercial farmers that use black plastic. In my own garden, I found that the drawbacks outweighed the benefits. Fertilizer applications were cumbersome and the plastic was in shreds by summer’s end. However, every gardening situation is different, and perhaps black plastic would work well for you.
Growing plants in blocks, rather than long rows, can save water, according to Colorado State University, and I’ve found this to be true in my own garden as well. Plants grown closely together shade the ground so water doesn’t evaporate as quickly. These plants also crowd out weeds and are simpler to harvest. Greens work particularly well grown this way.
Some plants don’t lend themselves to block planting, but it’s still a good idea to grow similar vegetables together. Tomatoes, peppers, and eggplants, for example, have slightly different water needs than watermelons and cucumbers.
Grow cool-season vegetables, such as lettuce, peas, carrots, and spinach, in the spring and fall. These vegetables thrive when the soil is moist and temperatures are cool. You probably won’t need to water them as much during the spring and fall due to seasonal rains.
Finally, how you use and apply water can have a profound impact on how much water you use. I’ve used soaker hoses in my vegetable garden for years and I prefer them to overhead sprinklers. Because the water is delivered directly to the ground, there’s much less evaporation. Soaker hoses can be arranged to deliver more water to dry areas of the garden. Using soaker hoses can also cut down on plant diseases. Wet leaves spread disease, so keeping them dry is important, especially if you live in a humid area. Soaker hoses can even cut down on weed growth by delivering the water only to where you need it.
Water your vegetable garden early in the morning – sunrise is not too early – if you have a system set to a timer. Otherwise, water as soon as possible. Water doesn’t evaporate as quickly in cool morning conditions. In very hot, dry regions, you might even water at night, especially if you’re using a soaker hose. Keep in mind, though, that this practice can encourage plant diseases if the leaves get wet.
Water your vegetable garden based on the plants’ needs, rather than a set schedule. The soil should feel moist one to two inches beneath the surface. You can also tell when plants need water simply by observing them. Vegetable plants might wilt slightly during afternoon heat, but they should rebound as evening approaches. Plants that remain wilted are not getting adequate moisture.