AUGUSTA — Only native plants will now be put in the ground on city properties.

City councilors earlier this year unanimously approved a new policy banning planting non-native plants in city parks and other property, a change recommended by the Augusta Conservation Commission to encourage plants that are better for native insects, animals and the local environment.

The policy applies to new and replacement trees, shrubs, herbaceous perennials and ground plantings on municipal properties.

The new policy does not apply to residential or commercial properties, only city-owned property, and there are exceptions including the planting of non-native annual flowers, lawns, and food-producing plants.

Some city councilors had previously suggested the city not require 100% native plantings, instead saying perhaps 70% would be a more achievable goal.

But Aaron Sienkiewicz, chairman of the Conservation Commission, said most cultivated landscapes throughout the city currently contain far below 70% native biomass. And that studies have shown some native animals, specifically chickadees, aren’t able to sustain their population in yards with less than 70% native biomass. So he recommended the policy require 100% native plantings, to increase the amount of native plants more quickly.

“By ensuring that all future plantings are 100% native, we help move toward that minimum threshold,” Sienkiewicz said in presenting revisions to the policy requested by city councilors during previous discussions of the proposal.

Under the policy, the city’s director of Parks and Recreation is able to grant exceptions to the planting rules, in consultation with the Conservation Commission.

Under the policy, plantings are required to be native to the Northeast, with a preference for plants native to Ecoregion 82 (Acadian Plains and Hills), an area that encompasses central and eastern Maine and parts of New Brunswick. Sienkiewicz said using that region was recommended by Gary Fish, state horticulturalist.

A list of native plants is available at plantfinder.nativeplanttrust.org/Plant-Search.

They include: sugar maple, white snakeroot, speckled alder, pearly everlasting, big bluestem, common winterberry, red cedar, mountain laurel, bayberry, winged sumac, chokecherry, black raspberry, common milkweed, fireweed, and sweet azalea.

The policy notes non-native plants don’t provide the same level of food and habitat that native plants provide for native insects, birds and mammals. As development increasingly encroaches on wild places, native flora has been destroyed, and often replaced by non-native plants in yards and gardens.

It further notes many non-native plants have become invasive, causing economic or environmental harm or harm to human health because some of them have no natural enemies here to keep their populations in check, allowing them to expand out of control.

Fish said previously that some native plants may be more difficult to propagate and thus more expensive. But he said as more nurseries offer native plants, the prices should come down.