Oh my, I never knew I was supposed to keep onions and potatoes separate. Since at this very moment they are in a not so cool tub sharing space, I will:
1. Put them in an empty clean bike basket.
2.Put it in a cooler place.
3.Segregate the onions from the potatoes.
Potatoes do much better in paper than plastic. In plastic the moisture does not get a chance to escape and they’ll rot in a heartbeat.
They HAVE to be kept away from light. Being exposed to light will cause them to turn green.
http://www.rittenhouse.ca/hortmag/horticulture&gardens/July01/Potato.htm
STORAGE OF POTATOES
For short-term storage place your potatoes in a cool dry dark well ventilated space at a temperature around 40 degrees F. For long-term storage, usually 6 months use a root cellar with all the short-term storage requirements. Always use the potatoes before they have sprouted. Remember Potatoes exposed to sunlight will turn green and these green parts are toxic.