AUGUSTA — Dozens of greenhouses, nurseries and garden centers are holding special events for the fourth annual Maine Greenhouse and Nursery Day.

Activities for Saturday’s event include giveaways, door prizes, demonstrations, tours, speakers and workshops to highlight the fun of gardening. The event is supported by the Ornamental Horticulture Council and the Mid-Maine Greenhouse Growers Association.

Agriculture, Conservation and Forestry Commissioner Walt Whitcomb says more than half the plants sold in Maine are grown in-state. Officials say the horticulture industry contributes more than $280 million to Maine’s economy each year.

A list of participating greenhouses and nurseries can be found on the Mid-Maine Greenhouse Growers Association website, http://www.plants4maine.com/GreenhouseAndNurseryDay.shtml .