DOUBLE THE RAIN
I have a little technique that I use with my compost. It can be used throughout the garden as well. It allows you to double the amount of rain you get!
I have one of those big colorful, plastic tubs with the rope handles standing right next to the compost bin. When it rains, the tub accumulates water. When it's done raining, I just dump that extra water into the compost bin. Since I've started doing this, the compost has never dried out. I used to drag the hose to the compost and water it to keep it moist. No longer! This works like a charm and it doesn't take a drop from our water system!
I see NO reason why this couldn't work in the garden as well. Put a few of the tubs in various places in the garden, maybe behind a shrub. Then after it rains, just empty it on the plants that need it most.
I will give you one cautionary note however. Mosquitoes breed in water, so don't let that water just sit there...you won't be happy!