Mary Barnett (above with a heritage tomato plant) has run the Mount Vernon Unitarian Church greenhouse at 1909 Windmill Lane, Alexandria, for many years with a team of volunteers, specializes in local native flowers, heritage tomatoes, and herbs. She grows most plants from seed in the 1930s art deco greenhouse that came with the Hollin Hall estate purchased by the church in 1959 in what is now the Mason Hill neighborhood off Fort Hunt Road. Best selling tomatoes this year are the dark ones, Barnett said: Black, Cherokee Purple and Black Krim. Other vegetables include hot and sweet peppers, eggplant, chard, kale, and lettuce. Herbs include several kinds of basil, dill, fennel, cilantro, marjoram, thyme, chervil, and several varieties of sage. Garden plants and flowers grown from seed are usually $2–$5, with some of the larger flowers up to $15. Proceeds go to keep the greenhouse in repair and purchase next year’s seeds.