Often you don't appreciate something until it's gone! That can really be true with water. Taken for granted when it is plentiful, its importance is truly appreciated in the garden once it becomes scarce.
If you find yourself in a drought, there are some things you can do to help conserve water and make the best use of what you have available. If you have not already mulched your plants, do it! Mulch will help limit the amount of water that evaporates from the soil. While organic mulches such as grass clippings or wood chips are preferable since they add organic matter to the soil, plastic mulches are useful in limiting evaporation from the soil. They can be laid between rows in the vegetable garden and will help limit moisture loss; however, they also will limit infiltration.
Place your water where it will do the most good. Sprinklers are very inefficient for getting water to the roots of your plants. Much of the water lands on the leaves and evaporates before reaching the ground. A slow gentle watering at the base of the plants, allowing the water to soak into the soil, will be most efficient.
Water those plants needing it most. Newly planted trees, shrubs, and flowers with limited roots systems will most likely suffer first from drought conditions. Give these plants priority if water is scarce. Well-established plants, especially those native to the area, are likely to withstand drought conditions with limited damage.
Water in the early morning before the heat of the day. This limits evaporation and supplies plants with needed moisture to make it through the hot, sunny day. Consider using drip or trickle irrigation systems. Many inexpensive, easy to install systems are available that provide small amounts of water to the base of individual plants. These systems place the water where it is needed most, rather than applying it across the whole garden. Check with your local garden center.
Collect water from downspouts when it rains. Roofs intercept significant amounts of rain. Collecting this runoff into a barrel can help limit the use of city or well water during dry spells.