UMATILLA, Florida — On an unusually cool October morning in Central Florida, farmer Bill Baker waited for a kindergarten group to finish touring greenhouses at Sunsational Farms in Umatilla. Today’s youngsters potted heads of lettuce, rode a tractor-towed kiddie train and picked mini-pumpkins. Sunsational is one of few Central Florida farms to grow its own pumpkins, Baker proudly states. Across the field, the Lake County farm’s “Big Orange” landmark structure sports a seasonal jack-o-lantern grin between hay bales piled with pumpkins and the farm’s co-operated Halloween haunt, Dr. Grimley’s Ha…