STOCKBRIDGE, Mass. — Berkshire Botanical Garden is a 24-acre botanical garden that showcases horticulture and garden design through its dozens of displays.   Starting May 1 the garden's grounds are open daily from 9 until 5 daily. Visitors can roam the grounds freely with no duration limit, but the average visitor often spends approximately two hours exploring.   The garden's mission is to educate and inspire the art and science of gardening and preserve the local environment.   This not-for-profit, membership-supported organization offers classes, lectures, workshop...