在不同的文化中使用DateTime的最佳实践是什么

I have asp.net site. On many pages is used datetime to be putted from user and then inserted or updated some db's table with it. My problem is that I have two version of site: local for testing (Ukraine) and production (USA). Because these sites have different culture datetime format are different. What is the best way to unificate workflows with datetime format? For example, I have page with textbox to be entered datetime in it and reqular expression validator. How can I do correct working with datetime in my local site ( dt format is dd.mm.yyyy) and production (mm/dd/yyyy) ? Thanks.I have asp.net site. On many pages is used date