Growth of containerized atlantic white cedar seedlings as affected by container volume, substrate, fertilizer, and irrigation

Abstract

Germination and growth of atlantic white cedar [Chamaecyparis thyoides (L.) B.S.P.] was evaluated in response to four container volumes (98 to 530 cm 3), two substrates [North Carolina Forest Service (NCFS) container mix [3 Canadian peat: 2 coarse vermiculite:1.5 perlite (by volume), and 3 composted pine bark:1 peat (by volume)], two controlled-release fertilizers [Osmocote 15N-4.0P-10.0K (15N-9P2O5-12K2O), 12- to 14-month southern formulation, with micros; and Polyon 18N-2.6P-10.0K (18N-6P2O5-12K2O) with micros, 9-month formulation], and three irrigation frequencies (2, 3, or 4 times daily). Although growth increased up to the maximum container volume (530 cm 3), the optimum for 1-year-old seedlings appeared to be 164 to 262 cm3. The higher peat content and water holding capacity of the NCFS substrate yielded better growth than 3 bark:1 peat. Osmocote yielded larger and heavier plants than Polyon, probably owing to more available phosphorus in the former. Irrigation three times daily was optimum. Suitable manipulation of container volume, substrate, fertilizer, and irrigation should yield high quality containerized atlantic white cedar seedlings.