How do your growlers seal? I bottle my Skeeter Pee in 12 ounce bottles and seal them with crown caps. While most of it gets consumed the same season that it is made, I do over-winter some for those who would like to try it in the winter as well as to have a supply ready for the first warm days of Spring. I haven't detected any problems with spoilage.
If your growlers are a tight seal, I think they should last fine until summer. If the seal is weak, changes in temperature or atmospheric pressure could cause gasses to push in and out of the bottle.