Although a cold-hardy vegetable plant, asparagus spears can be damaged when exposed to temperatures below 33 degrees F. Cover them with a thick cardboard box to protect them overnight from frost. Damaged spears will rot and new spears take four to five days to replace them, according to Iowa State University horticulturists.
About this Author
James Burghardt has written for "The Public Garden," "Docent Educator," nonprofit newsletters and for horticultural databases, becoming a full-time writer in 2008. He's gardened and worked professionally at public and private gardens in Colorado, Florida, Minnesota, New York, North Carolina and Pennsylvania. He has written articles for eHow and GardenGuides.