For many farmers, March is the calm before the storm of spring. But this year, in addition to ordering seeds and planning crops, small farmers around the country are finding themselves with very different tasks as the coronavirus outbreak upends their worlds: They’re remaking business plans, marketing new offerings and rewriting their sanitation rules.“I’m spending a lot more time behind a computer than I ever have,” said Shannon Varley, who co-owns Strafford Village Farm in Vermont with her husband, where they grow vegetables and flowers and produce beef, lamb and pork on 178 acres.