Secretary Trish Jarvie said the volunteers who had built up the Bunya Park garden, which held its opening day on Sunday, wanted to warn anyone who attended that any vegetables they had taken home may have been affected.

"Our members are devastated and angry," Ms Jarvie said.

"We warn anyone that took garden produce home after our opening event on Sunday not to consume the produce."

Plants in five raised garden beds and the one ground-level garden bed were found dead or dying on Wednesday evening.

That produce included seedlings donated by the Eleebana Kindy Patch children, which were planted to provide for a free food program.

The garden has no fences "because we want to welcome everyone into the garden".

Ms Jarvie said she had noticed some mild browning in the plants on Sunday but attributed it to the heat. 

She said members were "devastated and angry", and the matter had been reported to Lake Macquarie police.

"[We] always knew that community gardens have vandalism issues but not on the scale we have at the moment," Ms Jarvie said.

"Like everyone else who has heard about the destruction of the produce at our garden, I am struggling to understand why someone would want to destroy a community garden.

"All of our produce has been destroyed."

A working bee to restore the garden is planned for Saturday.

"We promise our community that we will clean up the garden and start all over again," Ms Jarvie said.

"Replanting will start as soon as possible."

​