A green-thumbed and environmentally-friendly group in Palmerston North will have been one of the first to celebrate Earth Day.

About 120 people turned out to plant 800 native trees in Awapuni's Waitoetoe Park on Friday afternoon.

Horizons Regional Council and Palmerston North City Council teamed up with the Friends of Waitoetoe Park to celebrate the environment and contribute to the area's preservation.

People of all ages from around the citytook half an hour to plant the trees.

Horizons environmental management officer Neil Mickleson said it was great to be able to tell the group that they were among the first in the world to celebrate Earth Day this year.

"It was just huge, and just a good blow out from the whole wider community," he said.

"It's just been magic to have so many people. Many hands make light work," he said.

Earth Day was designed as a day for people to think about the steps they could take on a daily basis to reduce their environmental footprint. This year's theme was Trees for the Earth.

"We're the first place to start Earth Day. It's just been great with a bit of music [so] the atmosphere has been great."

With a few drops of rain in the afternoon, everything was going to plan.

But there was plenty more to do, he said.

"Now there's a whole lot of other areas that we're looking at developing and planting up."

Horizons were looking into installing an irrigation system to make sure the trees would thrive, he said.