If your soil is dry, by all means water. However, you can slow down the evaporation when the weather is hot by adding a few inches of mulch. All sorts of materials are good mulch, including clean straw, leaves, weighted-down newspapers or finished compost.

Also, how is the organic content of your soil? If you are following SFG principles, you'll include peat moss and compost, along with vermiculite in your mix, and that should keep things moist for a longer time.

I have sandy, rocky soil and nutrients break down quickly, which is why I do square foot gardening; I can have much better control of soil conditions within a smaller, concentrated space.

All of my soil is compost, peat,sphagnum because of the clay soil that is useless here in Georgia. You cannot use any of the natural soils here unless you till and complement with LOTS of ammenities.I'll keep the straw in mind to conserve the moisture, thank you.