Cool temperatures Sunday night had cranberry growers in northern Wisconsin on frost alert.
On a chilly night, cranberry bogs can run many degrees colder than the average air temperature on the ground. Bob Winter runs Vilas Cranberry Company in Manitowish Waters. He says the mercury would have dipped below freezing in the bogs, if he hadn't turned on water sprinklers to help keep the plants warm.
“Low temperatures probably in the mid to upper 20s, so we started our irrigation system on about 9:30, 10 o’clock. And we water the vines, basically until the sun comes up and the temperatures start to rise…so about a 9, 10 hour run last night.”
Winter says this has been a late spring...but danger of frost at this time of year is nothing out of the ordinary.
"We watch it all growing season. Once we start we don't stop. You can have cool nights in July. So again it's nothing unusual for us...it's pretty much 24/7 for six months."
Once the sprinklers are turned on…Winter says they have to be checked regularly throughout the night.