I was issued a court summons in October for an incident that took place on July 9th 2013. On the summons I was issued it says on March 9th 2103 which is past the 6 months and also no where " on or near" July 9th. Is this summons invalid? will it help me have grounds to get off ?

Not sure about your state or jurisdiction. Suggest you call the number on the summons and talk to someone there.

You may be able to get the summons dismissed based on the errors, but it is not "invalid". You can't ignore the summons, but argue that the inaccuracy of the information should result in a dismissal.