Henry created and maintained gardens and greenhouses at the property where she lived. She cultivated a large kitchen garden, native rock plants, and orchards. Most of her knowledge came from foreign nursery catalogs and seed lists from the U.S. Department of Agriculture. She visited the Royal Botanic Garden in Edinburgh in 1923. Following her visit, she began corresponding with William Wright Smith, the Regius Keeper at the institution, until he died in 1956. She also corresponded with Francis Pennell, curator of botany at the Academy of Natural Sciences in Philadelphia. She went on biannual collecting trips starting in 1929 inspired by William Bartram whose description of "Rhododendron speciosum" inspired her search for interesting specimens that she couldn't find in commercial or botanical gardens. On her first collecting trip, her husband and four children joined her. Over the next forty years, she went on over 200 botanical expeditions.