Bush Beans: When To Plant

I've never had a problem with beans but last year was horrible.  I live outside of Redding CA where our summers are very hot (in the hundreds) but very dry.  Last year I planted on May 4th.  The beans germinated within a week, grew beautifully, flowered and then I got nothing or beans that were crescent shaped with nothing inside.  They got enough water (first time I used drip).  I spoke to numerous people and they all seem to indicate that it got too hot for them.  My questions:  should I plant the beans earlier this year?  I was thinking maybe next week sometime (3rd week of April) even though there is still a slight chance for frost.  I was also wondering if I should hose them down once in a while.  The other years I used irrigation sprinklers and never had this problem.  Any suggestions?