The root system of palms is adventitious and composed of numerous, small- to medium-sized, nonwoody roots. All primary roots are of a more or less constant diameter and arise independently from an area at or near the base of the stem called the root initiation zone (RIZ) (Tomlinson, 1990). Because of these root system characteristics and the ability of their trunks to store water and carbohydrates (Tomlinson, 1990), palms are relatively easy to transplant—even large specimens with small root balls—resulting in instant, mature landscapes. In contrast, the woody, branched root systems of dicotyledonous and coniferous trees require that a much larger root ball be secured to ensure establishment of these types of trees, increasing the difficulty and expense of transplanting large specimens.
The basic element of successful establishment of transplanted palms is the rapid generation of new roots from the RIZ and/or the regeneration of new root tips from cut existing roots. A number of important factors, such as plant maturity, the time of year, root ball size, leaf removal and tie-up, planting depth, the use of soil amendments in the backfill, mulching, and irrigation management, can influence the success of palm transplanting.
For clarity, we define transplanting in this article as the digging of palms in the landscape or field production nursery and then planting them into the new landscape. Typically, transplanting palms results in a significant reduction of their root system, and the process generally requires special handling practices to ensure successful establishment and survival. In contrast, planting containerized palms, where the root system is mostly intact, results in little or no root loss or disturbance, and is a much simpler and less exacting process. Although this article primarily addresses issues relating to transplanting palms, many of the factors presented and discussed below can also affect establishment of containerized palms.
Broschat, T.K. 1994 Effects of leaf removal, leaf tying, and overhead irrigation on transplanted pygmy date palms J. Arboriculture 20 210 213
Broschat, T.K. 1995 Planting depth affects survival, root growth, and nutrient content of transplanted pygmy date palms HortScience 30 1031 1032
Broschat, T.K. 1998 Root and shoot growth patterns in four palm species and their relationships with air and soil temperatures HortScience 33 995 998
Downer, A.J. & Hodel, D.R. 2001 The effects of mulching on establishment of Syagrus romanzoffiana (Cham.) Becc., Washingtonia robusta H. Wendl. and Archontophoenix cunninghamiana (H. Wendl.) H. Wendl. and Drude in the landscape Scientia Hort. 87 85 92
Hodel, D.R. & Pittenger, D.R. 2003 Studies on the establishment of date palm (Phoenix dactylifera ‘Deglet Noor’) offshoots. Part I: Observations on root development and leaf growth Palms 47 191 200
Hodel, D.R., Downer, A.J. & Pittenger, D.R. 2006a Effect of leaf removal and tie up on transplanted large mexican fan palms (Washingtonia robusta) Palms 50 76 81
Hodel, D.R., Downer, A.J., Pittenger, D.R. & Beaudoin, P. 2006b Effect of amended backfill soils when planting five species of palms HortTechnology 16 457 460
Hodel, D.R., Pittenger, D.R., Downer, A.J. & Richie, W.E. 2003 Effect of leaf removal and tie up on juvenile, transplanted canary island date palms (Phoenix canariensis) and queen palms (Syagrus romanzoffiana) Palms 47 177 184
Pittenger, D.R., Hodel, D.R. & Downer, A.J. 2005 Transplanting specimen palms: A review of common practices and research-based information HortTechnology 15 128 132