Greenhouse Culture and Production of Four Ornamental Native Wetland Plants

Wetland restoration is an important way to improve ecosystem services, but many wetland nurseries lack the facilities that are traditionally used to produce large numbers of native plants used in these projects. Our goal was to evaluate growth and performance of four wetland species in a variety of substrates, fertilizer regimes, and irrigation methods under greenhouse conditions. Plants were grown in pots with drainage holes filled with one of four substrates (potting substrate, topsoil, sand, 50/50 mix of topsoil, and sand) amended with 0, 1, 2, or 4 g of 15N-3.9P-10K controlled-release fertilizer per liter of substrate. Irrigation was supplied via an overhead system or subirrigation. After 16 weeks of production, plants were scored for visual quality and plant height before a destructive harvest. Broadleaf sagittaria (Sagittaria latifolia) was mostly unaffected by substrate type but performed best when subirrigated and fertilized with 4 g.L L-1 of fertilizer. Growth of skyflower (Hydrolea corymbosa) and cardinal flower (Lobelia cardinalis) was best when fertilized with 2 or 4 g.L L-1 of fertilizer and grown using overhead irrigation. String lily (Crinum americanum) was unaffected by substrate type but produced the largest plants when subirrigated. These experiments provide guidance for cultivating these wetland species under greenhouse conditions, which may allow growers to efficiently produce plant material needed for the restoration market.