Growth of Viburnum dentatum and Syringa × prestoniae ‘Donald Wyman’ in Sphagnum Peat and Coir Dust-Based Substrates

Abstract Bare-root viburnum (Viburnum dentatum L.) were grown in 25:0:75, 50:0:50, 75:0:25, 100:0:0, 0:25:75, 0:50:50, 0:75:25, and 0:100:0 peat:coir:sand (by vol) substrates, and Preston lilac (Syringa × prestoniae McKelv. ‘Donald Wyman’) were grown in 25:0:65:10, 50:0:40:10, 75:0:15:10,0:25:65:10, 0:50:40:10, and 0:75:15:10 peat:coir:bark:sand (v/v) substrates over two seasons. After one season of growth, viburnum grown in 25% and 50% coir were taller than plants grown in comparable peat-based substrates, and overall, plants grown in coir-based substrates were taller than plants grown in peat-based substrates. Lilac plants grown in coir-based substrates had similar heights as plants grown in peat-based substrates. After two seasons, viburnum grown in 100% coir had greater plant width than plants grown in 100% peat. No significant difference occurred between plants grown in 25% and 50% peat or coir. No significant difference occurred in shoot fresh mass between viburnum plants grown in coir and peat-base...