Hostess with the mostest Martha Stewart will celebrate her 70th birthday at her Skylands home in Maine this weekend. Stewart’s daughter, Alexis, and new granddaughter, Jude, will attend, and the guest list will be comprised of close friends, colleagues and neighbors, sources said. There’s already been some buildup to the big day. Martha Stewart Weddings editorial director Darcy Miller threw a birthday party for Stewart and invited her creative team in New York this week. Up in Maine, the décor doyenne and chef Pierre Schaedelin — who collaborated on Stewart’s upcoming “Martha’s Entertaining” tome — are expected to whip up big breakfasts and lobster roll lunches between activities including exploring local islands and picnicking aboard Stewart’s boat, Skylands II. “She loves to hike,” said a source close to Stewart. “There will be good food, and they’ll do all the things Martha loves to do in Maine.”