Soil management is a major part of every gardener's life. The longer you've been working with plants, the more you realize that they can only thrive if the soil they're growing in is also a thriving, balanced mixture. Choosing your soil, however, is deeply connected to your local climate — which is exactly why hot, dry zones tend to experience some unique issues. If you anticipate hot weather and low rainfall over the next few weeks, consider how these techniques can help your soil maintain high enough moisture levels to keep your plants healthy and happy. If you are using an irrigation system, you'll be amazed at how much water you save when these techniques are in play.
Mix In Organic Matter
Many soils tend toward either the sandy side, draining away the water they receive almost immediately, or the clay side, which compacts and makes it hard to access water even if it is retained for a long time. One of the best ways to aid any type of soil is to add in organic matter like compost or peat moss, either of which will do a good job of absorbing water and draining it away over time. The added benefit of organic matter is that it also feeds the soil, pumping it full of nutrients that the roots are trying to find anyways. Using these amendments each year will not only help your plants grow, but it will also give them continuous access to the water they need on those particularly hot days.
Make Mulch Your Friend
A layer of mulch can be good for avoiding excessive evaporation on hot days. A layer of wood chips, for instance, may get very hot, but the water that has drained through them into the soil will take much longer to evaporate back out again. Choose your mulch based on the hardiness zone you live in, the materials that are native to the area, and the ones that will work well for your particular plants. Always remember that a thick layer of mulch is great for cutting down your irrigation duties. You'll still need to move it aside a little to evaluate how dry the soil is, but it will be well worth the effort.
Maintain a Weeded Bed, but Use Those Weeds!
Most people don't think of weeding this way, since they tend to weed gardens simply to maintain the health of their plants and the beauty of their garden beds, but weeding is actually an excellent moisture-saving measure, too. For one thing, weeds greedily slurp up the water that could otherwise be used by your preferred plants. When you weed a bed, however, any truly removed specimens will often desiccate in the sun, with part of that moisture adding positively to the surrounding environment. If you worry about weeds re-rooting and coming back as even stronger weeds, you can place all the organic matter you've weeded into a compost bin, where the moisture will aid in the process of turning everything into useful future soil.
Try Polymer Moisture Crystals
If your plants are still drying out too quickly, you make want to try a synthetic approach. Look for polymer moisture crystals at the local nursery. These crystals work by swelling up like gelatin when they encounter water. Rather than letting most water drain or evaporate away, they slowly release their moisture, keeping the plants exposed to water for a much longer period of time. While not technically a "natural" solution in most environments, these little guys can be incredibly helpful for gardeners who aren't ready to run soaker hoses or complex irrigation systems through their beds but who still want all-day moisture for their plants.
Choose Plants That Fit Your Environment
One of the most effective strategies for maintaining soil moisture at levels that allow plants to thrive is a bit of a cheat: just use plants that are already accustomed to the environment where you are living! Many of us choose plants based on what appeals to us and what looks beautiful, but some of those plants won't be easy to grow in a hot, dry climate. If instead you choose plants that can already survive and stay hardy under hot and dry conditions, your watering efforts won't have to be so relentless. The techniques above still apply, but they will work much better and produce a more vibrant garden if the plants in it are already used to the hardships of dry soil.
By choosing the right kinds of plants, weeding extensively, and amending your soil in ways that will make it retain more water without becoming waterlogged, you can create a positive garden environment. This soil will be more likely to produce the kinds of beautiful flowers, fruits, and vegetables that you desire, even in hot and dry climates, and you won't waste any water when irrigating. A practical gardener can save him or herself a lot of time by making mulching and organic matter a priority from the first day of the growing season.