National Tree Day will be observed on Sunday, however efforts to plant a forest of native animal-friendly trees, in particular for koalas, will begin in Raymond Terrace on Wednesday and will continue in Tanilba Bay, Mallabula, Nelson Bay and Corlette into the weekend.

Fran Corner, president of Tilligerry Landcare, said the group was working on planting 20,000 koala food trees on the Peninsula which would which would assist Port Stephens Koalas' hospital once it was up and running.

"We've been working on and off for six years to plant a koala forest," Ms Corner said.

"There's a need now more than ever to plant as many koala food trees as we can so in five years time Port Stephens Koalas can just come to a certain spot and collect leaves for the koalas in the hospital, because they're going to need a lot."

Tilligerry Landcare is calling on volunteers to help it plant more trees in the Tilligerry Koala Forest on Sunday between 11am and 3pm.

For the past six years Landcare volunteers have worked to establish a forest filled with native animal-friendly trees at Mallabula Sports Complex, to the rear near the soccer and athletics fields.

Trees that were planted this time last year at the forest site, which was a sand mine in the 60s, have already grown 1 metre tall.

"We know there's quite a few animals that live in this forest," Ms Corner said.

"We set up one of those wildlife cameras and saw Eastern grey kangaroos, a wallaby, possums and echidnas.

"It's important that we plant more trees here, for the native animals and for the koala hospital."

All are welcome to attend Tilligerry Landcare's tree planting event on Sunday. Volunteers are asked to meet in the eastern carpark of Mallabula Sports Complex, near the soccer club, and to take along a shovel.

Volunteers are also being sought to help with tree planting efforts in Corlette and Nelson Bay across the weekend.

The Mambo-Wanda, Soldiers Point-Salamander Bay and Corlette Landcare groups plus Port Stephens Koalas will combine on Sunday to plant koala food trees and other Australian shrubs and grasses in Vantage Estate at Corlette between 10am and 1pm.

Volunteers are asked to meeting at the top of Gawul Circuit, near Guyang Street, and to take along digging tools, small mattocks or shovels, buckets or bottles for water and to wear covered shoes.

More volunteers are being sought to help weed couch grass at One Mile on Sunday between 8am and 10am. Meet in the One Mile Beach carpark.

Preschool and primary-aged children were set to help plant trees in Boomerang Park, Raymond Terrace on Wednesday and in Gula Park, Tanilba Bay on Friday.