CHICAGO (CBS) — One of the Chicago Park District’s most popular attractions has planned a big party on Earth Day, when it will reopen greenhouses that suffered severe damage in a hailstorm four years ago.

On Wednesday, all show rooms at the Garfield Park Conservatory will reopen for the first time since the start of a three-year, $15 million restoration project to repair glass roofs shattered by hail on June 30, 2011.

Most of the plants survived the storm, but 31,000 glass panes at the conservatory were destroyed, including the roofs of the Fern Room, Desert House, Show House, and 10 propagation greenhouses.

While the damaged greenhouses reopened within months of the storm, after installing temporary roofs, they were closed again in 2012 so the glass could be replaced with double-paned laminated glass that is much stronger, and tested against hail damage. As part of the three-year, $15 million repair project, wood framing also was reinforced to handle the extra weight of the heavier new glass.

On Wednesday, the conservatory will celebrate the grand reopening of its full campus, with the Fern Room and Desert House open for the first time since the latest extensive repairs. It will host a series of free public events and performances from 9 a.m. to 8 p.m. Wednesday. It will also hold a Family Day Celebration on Sunday, from 9 a.m. to 5 p.m.

For full details on the celebrations, click here.

About 160,000 people visit the Garfield Park Conservatory every year. The conservatory contains more than 1,300 varieties of indoor plants, and 300 species of outdoor plants. It first opened to the public in 1908.