Here is a link to advice on what you should be doing and watching for in your garden in July.
http://learn2grow.com/regional/2009/07/regional.aspx?markref=rotor3-July3-9
Here are a couple of examples of what you will find (these are for the Southeast Region):
Continue to harvest vegetables in your garden as they ripen, and remember to share any excess produce – perhaps with a food co-op or shelter. (This is a thoughtful act of kindness, as well as a great lesson for the kids!)
Replace any annuals that perform poorly in high heat and humidity with more tolerant annuals. But be warned: Heat-tolerant plants don’t exhibit such tolerance until they’re well-established, so be sure to care for them well after planting!
Bugs are a big problem this time of year. This site has a list of what bugs to watch for in each region as well.