30 Things You Might Not Know About the Climatron

The Climatron® is an architectural marvel filled to the brim with tropical plants from all over the world. A lot has happened in the 60 years since it first opened to the public. From history to pop culture, and even an alligator encounter, here are 30 things you might not know about the Climatron.

In celebration of its 60th anniversary in 2020, we’re sharing stories about the Climatron through the years. Visit our Climatron 60 page for historic photos, video, and more.


The Climatron is the first geodesic dome to be used as a conservatory. It was based on the design of R. Buckminster Fuller and developed by St. Louis architectural firm Murphy and Mackey.


The Climatron replaced the old Palm House. Efforts were made to save the existing palms, but a cold-snap killed 11 of the tropical trees in 1959 before the dome could be completed.


A number of plants growing in the Climatron today did survive the construction, including several cycads that have been at the Garden for more than 100 years and are likely much older than that.


An evergreen tree marked the “topping out” or completion of the structure, without accident. The Northern European custom dates back about 1,300 years.


Admission to the Climatron was initially 50 cents, and visitors were given tokens for entry. Today, the Climatron is free with regular Garden admission.


The Climatron has 2,425 window panels. Originally made of Plexiglas, they were replaced with heat-strengthened glass and Saflex as part of the 1990 renovation.


The Climatron is 70 feet high and 175 feet in diameter. It encloses a volume of 1.3 million cubic feet.


There are about 3,000 plants in the Climatron ranging from tall palms to delicate orchids. Because of its tropic-like atmosphere, the Garden can safeguard threatened plants such as the blue Mauritian bellflower.


The Garden borrowed an American Alligator from the St. Louis Zoo in 1970 as part of a study on energy output. The alligator was housed in a fenced area behind the Climatron, now home to the Children’s Garden. Read more about the study here.


The original Climatron included the Aquatunnel, allowing visitors to view the underside of aquatic plants, such as Victoria water lilies. The Aquatunnel was removed during the renovation in 1990.


The Garden’s annual Orchid Show was held in the Climatron from 1971 to 1982. Today orchids are displayed in the Climatron year-round on a rotating basis.


Before settling on Climatron, the Garden considered other names like “Plantosphere,” “Sylvarium” and “Floradome.” The name Climatron emphasized the revolutionary indoor climate-control system.


The average temperature inside the Climatron is 85 degrees during the day, and 64 degrees at night. The average humidity is 85%.


Weather conditions under the dome can sometimes cause clouds to form inside the Climatron. You may also notice a temperature change as you walk from the upper to lower level.


The trees in the Climatron need to be trimmed annually to avoid bumping into the glass dome overhead. Watch a video about that process here.


The Climatron housed roseate spoonbills on loan from the St. Louis Zoo, as seen in this photo from 1971. Ducks, pheasants, hummingbirds, a toucan, iguanas, and butterflies were also part of the loan program.


Today, the Climatron is home to much smaller animals, including silver tanagers, guppies, and geckos. These animals help the plants by eating insect pests.


The 1961 Garden master plan called for a series of smaller domes connected to the Climatron, along with a symphony hall and a new research facility. Only the Climatron was ever built.


The Garden invited the public to help name areas in the new Climatron, such as “Little Hawaii,” “Misty Ridge,” and “Emerald Mountain.”


The Climatron was intended as a living laboratory, and still serves that purpose today. Botanists like Monica Carlsen use the space to train future plant scientists.


The Climatron was the inspiration for the space conservatories featured in the 1972 movie Silent Running, starring Bruce Dern. In the movie, the domes hold a variety of plant and animal life for the eventual reforestation of Earth.


An animatronic talking orchid was one of the highlights of the renovated Climatron when it opened in 1990. It was removed because of technical problems, but you can still listen to the original audio on our blog.


The Climatron helped double Garden attendance in 1960 compared to the 10-year average of the previous decade. 4,000 people visited in the first week.


For a number of years after it first opened, the Garden offered nighttime visitation hours, keeping the Climatron lit with large lights, and open until 9 p.m.


The Climatron once had an elaborate lighting system meant to replicate bright tropical sun and moonlight. The floodlight assembly could rotate to shine light on different areas of the interior.


In 1976 the Climatron was named one of the 100 most significant architectural achievements in U.S. history.


Other geodesic dome conservatories include the Eden Project in England, the Bloedel Conservatory in Vancouver, and the conservatory at Des Moines Botanical Garden in Iowa.


The Climatron has provided a tropical backdrop for photo shoots for decades. It was even featured in a YouTube music video.


The cast of South Pacific visited the Climatron during the show’s run at the Muny in 1969. The Garden also supplied live plants for the production.


The Climatron has hosted many art and sculpture shows over the years, most recently serving as the setting for Garden of Glass: The Art of Craig Mitchell Smith in 2017.

Cassidy Moody
Senior Digital Media Specialist

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