Compost Amended Media and Irrigation System Influence Containerized Perennial Salvia

Abstract

Three perennial species, wine sage (Salvia spp. Sell x roenen Schultes `Van Houttei'), blue anise sage (Salvia gauranitica St.-Hil. Ex Benth. `Black and Blue'), and indigo spires salvia (S. longispicata Martius Galeotti × S. farinacea Benth. `Indigo Spires') were transplanted in containers filled with a biosolid-yard waste compost, a commercial peat-based mix, or a mixture of 1 compost: 1 peat-based mix by volume) and grown under ebb-and-flow, drip, or manual irrigation systems. Initial physical, chemical, and elemental analyses of the media indicated that compost alone had higher pH, electrical conductivity (EC), total porosity (TP), bulk density (BD), particle density (PD), N, C, P, Ca, Zn, Cu, Fe, and B; lower initial moisture, Mg and Al; and similar Mn contents than did the 100% peat-based medium. Heavy metal (Cd and Pb) contents of compost did not exceed EPA 503 Rule limits for biosolid usage. After 6 weeks, plants were measured for leaf nutrient content, growth (leaf and stem dry weights, stem lengths), and quality (number of flowers, leaf greenness, and subjective quality ratings). At 6 weeks, plants grown in 50% or 100% compost generally had higher leaf K, P, and Mn; similar N and Ca; and lower Mg, Fe, and Al content than plants grown in the 100% peat-based medium. Plants grown in media amended with compost generally produced similar or slightly smaller plants (stem weight, leaf weight, and stem length) than when grown in peat-based media. Plants irrigated by ebb and flow resulted in higher (`Van Houttei') or similar (`Indigo Spires') dry stem weights than plants irrigated manually or with drip irrigation. Plants grown in compost had leaf SPAD readings (leaf greenness), number of flowers, and visual quality ratings that were generally similar (`Indigo Spires') or slightly reduced (`Van Houttei') than plants grown in peat-based media. However, for each species (except for `Van Houttei' grown in 50% compost using drip irrigation), plants were of marketable quality, regardless of irrigation system or medium. This study suggests that compost may serve as a viable alternative substrate for peat in the production of containerized perennials using ebb-and-flow, manual, or drip irrigation systems.