Two weeks is a long time -- throw it out and make some fresh nectar.

Nectar life depends on the temperature outside. During winters when daytime temps are colder than the fridge (just above freezing), a week or more is fine. When it's warmer, you might change it every 2 to 3 days.

Some visible signs that the nectar is getting bad -- cloudy liquid (good nectar is clear like water), black growths inside, floating bugs, etc. If it looks icky enough that you wouldn't drink it, change it. Clean the feeder thoroughly and rinse rinse rinse before refilling.

I have heard not to clean your feeder with soap, it leaves a residue that they don't like. You can bleach your feeder once a week or two weeks. Keep looking!!

When I get in the 90s here (supposed to be the end of this week) I change it daily, 80's every other day and 60's and 70's every three days. I don't like to wait until I see it clouded and moldy. When I don't get a lot of visits I only fill about a cups worth and keep the rest in the refrigerator for safe keeping. I think it is good for up to a week in the fridge.

Mine will smell fermented, which is way to old. It happens in just a few days in hot weather.

You should change the nectar every 2-3 days and possibly more when it is hot and humid. It will ferment and the hummers will look elsewhere for a fresh source or if they do drink it, it could make them ill. I am in the northeast and I change out the nectar and clean the feeders with white vinegar every other day.

Penny

I'm a fanatic about cleaning my single feeder. I don't want to take any chances of making the birds sick. I clean it every day in warmer weather, but don't use any cleaning solutions. I just give it a preliminary rinse, and toss it into a pot of water and boil it for 20 minutes or so. It's not that I'm against vinegar or bleach, I just never got into the habit of using them!

I agree that in cooler temperatures, it would be okay to leave the solution for 2 or 3 days, I just don't like to take chances.

hhuuummm I thought I could squeek a week out of it here in West Michigan at this time of year but I will go out and change it, it has been 3 days. I expect them to be here any minute and I want to be sure to welcome them properly!
BTW Kristin were you ever a figure skater? (just cause I know a skater with the same name that moved to PA years ago)
Lisa