I made up a 1:1 batch of sugar syrup yesterday in anticipation of receiving my bees today. My supplier, a few towns over, called and asked if he could post-pone delivery one week. Now, I've got a couple gallons of sugar syrup made up with no bees to feed it to. How long will it keep? I'll store it inside, but don't have room for it in the refrigerator. Is there anything I can do to extend its shelf life?