Plant small trees under big trees. This will help prevent evaporation and provides some shade for your plants. You can also plant a shade garden under trees.Use mulch on your garden to retain moisture. Ideal mulch candidates include hay, manure, leaves, wood chips, bark, and newspaper. Many mulches are available for free or very low cost. The right organic mulch can also help improve your soil as it breaks down and keep weeds in check. Know how much water plants need to thrive, and dont apply more water than that.Grow plants with like water needs together. Sometimes called hydro zoning, this method simply means that plants are grouped together by water use, so that they can all be watered appropriately.Use furrows and basins. Dig low areas to water only the root zones of your plants, not bare areas around them.