Most modern gardens in hot climates use drip irrigation to conserve water. The problem with drip irrigation is that it cannot deliver enough water to many plants for them to survive 100 degree heat. Drip irrigation works well for 10 months out of the year but in the summer on days where the temperature is extreme many plants will wilt, burn and possible even die.
I have found a solution to this problem in my garden in Grass Valley, CA, Dawn Gardens. When the forecast predicts that the temperatures will be over 100 degrees I start watering the garden with sprinklers in addition to the automated drip system. Once a month each area in the garden will get a deep watering. I move the sprinklers around to the driest areas and leave them on until the soil is saturated at least 12″ deep for shrubs and perennials and 24″ for trees.
I can do this at Dawn Garden because I use cheap canal water for irrigation. But even if you have city water that costs 1 cent per gallon you can do it for less than $75 per month in the summer. Example: 6 settings (for a small garden) x 4 hrs. per setting x 60 min./hr. x 5 GPM x $.01/gal. = $72.