WASHINGTON • During the recent government shutdown in the United States, Smithsonian horticulturist Virginia Thaxton continued to work. She walked into the closed, dimly lit, empty museums once a week.

"It was eerie," she said of walking alone among the artefacts in the usually bustling buildings.

Ms Thaxton also kept up her work at the Smithsonian Gardens Greenhouse, preparing for the annual Smithsonian Gardens and United States Botanic Garden (USBG) orchid exhibition, where hundreds of orchids are on display.

The shutdown delayed the exhibition by only two weeks because the horticulturists, gardeners and technicians were still working hard to keep the orchids and other rare plants healthy.

Both the Smithsonian and USBG have huge greenhouses that mimic the light, temperature and humidity of the plants' native environments.

The greenhouses are long, rectangular glass buildings that open into bays large enough to drive a truck into so plants can be moved without being exposed to the elements.

Ms Thaxton has been working with rare plants at the Smithsonian Gardens Greenhouse for years. "There are at least two horticulturists working in the greenhouses 365 days a year," she said.

In addition to 8,000 orchid plants, the Smithsonian Gardens Greenhouse in Suitland, Maryland, produces the plants inside and around all Smithsonian museums.

There is even a special greenhouse for the nectar-source plants that feed the butterflies in the butterfly pavilion at the National Museum of Natural History.

The USBG Production Facility has about 4,000 orchids in three greenhouses.

It sends plant waste to be composted and then brought back to the facility to be used.

The Smithsonian uses some fertiliser, but not poop from the National Zoo. Why not? The zoo animals do not digest everything completely, so manure is full of seeds, which sprout and cause confusion between what was planted and what is leftover from the animals.

The Smithsonian facility is not open to the public. But USBG opens its 7,896 sq m (nearly 0.8 ha under glass) production facility in Southwest Washington to the public for one day each year.

This year's open house is next Saturday. Visitors have to reserve tickets and they usually sell out in advance. For a private tour, young visitors can become a junior botanist by following the steps on the USBG website, which includes activities to do at the conservatory and at home.

Ms Thaxton said one of her favourite things about working with orchids in warm, humid greenhouses is that the setting reminds her of her native Colombia.

That is an extra selling point for touring USBG's facility. It is a tropical escape without leaving the US capital.

WASHINGTON POST