How long can apartment management hold your check before processing it?

As long as they want.

My bank will honor any check less that 9 months old. At my son's bank it's 3 months. So I quess it depends on bank policy.

They can hold it as long as they want... they may have problem cashing those checks depending on bank's policies, but you are still liable for your rent. If they are likely to be late, you should send money order instead of check. Keep record for your file.

Are you sure they have the check?

I've always heard a check is invalid after 6 months... check with your bank...

First why are they holding the check, did you ask them to hold it, or are they just slow in processing the check .