Power-washing 2,425 panes of glass is tough, especially when they’re cut and placed at odd angles. Maybe that’s why it had never been done.

When the Missouri Botanical Garden in St. Louis built the domed greenhouse known as the Climatron in 1960, it was encased in Plexiglas. It was then rebuilt in 1988 using real glass. But it had never been washed -- that is, until this past spring.

With an exhibit of glass sculptures going in, spiffing up the place seemed in order. The entire job, inside and out, took about nine weeks.

Still, they couldn’t clean it all. A lift capable of reaching the very top would have been so heavy it would have crushed the concrete walkways around the dome.