The 2012 ASHS Annual Conference

A common, standard industry practice to use straight builder's sand as the sole backfill medium when transplanting palms has no research basis. In a study conducted at Irvine California, queen palms [Syagrus romanzoffiana (Cham.) Glassman], Chinese windmill palms [Trachycarpus fortunei (Hook.) H. Wendl.] and king palms [Archontophoenix cunninghamiana (H. Wendl.) H. Wendl. & Drude], were transplanted using either unamended sand or native site soil as the sole backfill material. After 2 years, backfill medium had no effect on new leaf production in queen and Chinese windmill palms but king palms produced an average of 800% more leaves with sand backfill. Backfill medium had no effect on the percent of the leaf canopy that was green for any species. Of the portion of the canopy that was green, backfill medium had no effect on the intensity of green color in queen and Chinese windmill palms but sand backfill improved green color in king palms by one full rating mark (5-point scale). All queen palms survived regardless of backfill medium. All Chinese windmill palms with sand backfill survived compared to 80% survival with soil backfill. For king palms, 60% survived with sand backfill while 40% survived with soil backfill. While growth and color of queen and Chinese windmill palms were similar regardless of backfill material, growth, color, and survival of king palms was improved with sand.