For Caitriona Balfe's birthday, Outlander fans planted 150,000 trees.

To commemorate lead actress Caitriona Balfe's birthday in 2020, a group of Outlander fans created Project CaiTREENa.

The massive tree-planting initiative started by a group of environmentally aware Outlander fans is now in its fourth year.

To celebrate lead actress Caitriona Balfe's birthday in 2020, a group of devoted fans of the internationally popular time-travel drama set in Scotland created Project CaiTREENa.

The campaign has grown steadily and now has thousands of supporters worldwide, many of whom will be extremely busy today when the Claire Fraser actress turns 44.

The initiative, which was first intended to plant only one tree in honor of the former Irish model's birthday in October.

Has now resulted in the extraordinary planting of 150,000 trees as part of a global "Balforest."

The women connected on social media during the epidemic and have since welcomed a large number of admirers as well as some of Caitriona's co-stars, increasing their forest from 410 trees to over 150,000.

Each $1 donated by the group meant a new tree thanks to their collaboration with the non-profit environmental tree planting organization One Tree Planted.

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