The Boulder Valley School District’s annual plant sale starts May 10. The sale is open from 4 to 6 p.m. May 10, 8 a.m. to 4 p.m. May 11, 4 to 6 p.m. May 17, and 8 a.m. to 4 p.m. May 18. The sale also will open early for Boulder Valley staff members, who get a 25% staff discount, from noon to 4 p.m. May 10.