Horticultural Arts Society Annual Spring Plant Sale at the Demonstration Garden in Monument Valley Park. Featuring seedlings and mature Colorado-grown plants. Call 475-0250 for details. Fri.-Sat., May 17-18, 5 p.m. Sun., May 19, 10 a.m. to 4 p.m.
In Their Honor Fly-In, a WWII-era airshow at the former Colorado Springs Airport. Featuring aircraft ranging from bombers to modern helicopters. $5-$8, 635-8803. Sat., May 18, 9 a.m. to 6 p.m. Sun., May 19, 10 a.m. to 5 p.m.
Colorado College Commencement Ceremony featuring a speech by Mihaly Cskiszentmihalyi on Armstrong Quad. Free. For details, call 389-6265. Mon., May 20, 8:30 a.m.