MONTGOMERY-Celebrate fall with a botanical twist. The Friends of the Orange County Arboretum will hold its Harvest Festival from 10 a.m. to 4 p.m. on Saturday, Sept. 25. Visitors can watch a demonstration by the South Eastern Beekeepers Club, which will harvest honey from the Arboretum's beehives for the public to sample and buy. Professional beekeepers will be on hand to discuss the importance of the honeybee the pollination of plants and to healthy lifestyles. Diana Weiner, superintendent of grounds for Mohonk House, will lead visitors in an educational tour of the Arboretum at 10 a.m., to identify trees, plants, and aquatic life. Caroline DeWilde of the New York Botanical Gardens will be available to answer visitors' thorniest horticultural questions. And arts and craft vendors will be selling specialty items. Located in the Thomas Bull Memorial Park on Grove St., off Rt. 416 in the Town of Hamptonburgh, the Arboretum features raised gardens, paved paths, a water feature, and the Sept. 11th Remembrance Walkway and Garden. This free event is in cooperation with the Orange County Department of Parks, Recreation and Conservation. For information, call Paula M. Gorton at 457-4902.