Since the Reminders app for iPhone and iPad can use your location to dish up reminders based on where you are, Siri can add location-based reminders for you as well. Simply tell Siri what you need to be reminded of, and where, and you're done!
How to create a location-based reminder with Siri
Press and hold the Home button on your iPhone or iPad to launch Siri.
Say something like "Remind me to make a shopping list when I get home."
Siri will then confirm what she heard. If you need to change something, just tap the text to edit it, or start over.
Once things look right, tap Confirm and Siri will add the reminder.
That's all there is to it! Siri will remind you when you get to that specific location. Keep in mind that in order for Siri to know locations, you need to have them in your Contacts app. For example, on your own contact card, save your home address. If you want Siri to remind you of certain things at specific stores, you'll need to have contact cards for them with the address saved.