Ornamental Landscape Performance of Native and Nonnative Grasses under Low-input Conditions
Authors: Thetford Mack , Norcini Jeffrey G. , Ballard Barry , Aldrich James H. 
Published: August 2023

Full sun trial gardens (full sun) were established at Leon County (LC) and Santa Rosa County (SRC), Florida, to evaluate the effect of site on horticultural performance traits pertinent to landscape use (long-term growth, flowering, vigor, overall quality, and survival) of native and nonnative warm season grasses when grown under low-input landscape conditions over a 3-year period. The gardens contained landscape fabric- (LC) or plastic (SRC)-covered rows, with the synthetic mulch at each site covered by 4 inches of hardwood chip mulch. Fifteen native and eight nonnative grass species, and cultivars were evaluated as were the two grass-like species black flowering sedge (Carex nigra) and narrowleaf silkgrass (Pityopsis graminifolia), a native dicot with grass-like foliage. Many of the native species were derived from seeds or plants collected from naturally occurring populations in Florida, and other species or cultivars were obtained from commercial sources. Based on quality ratings and survival, a majority of the species and cultivars were rated as at least being marginally acceptable for 2 years or more, but only six species and cultivars were rated as excellent or good over all 3 years. Four of these six species were native, with 100% survival at both sites occurring only for purpletop tridens (Tridens flavus). The other three native species, gulf hairawn muhly, (Muhlenbergia capillaris var. filipes), ‘Alamo’ switchgrass (Panicum virgatum), and indian woodoats (Chasmanthium latifolium) had high rates of survival. Porcupine grass (Miscanthus sinensis ‘Strictus’) and ‘Cabaret’ silver grass (M. sinensis ssp. condensatus) were the only two nonnative species demonstrating potential for long-term performance in a low-input landscape at both sites. Three of the four cultivars of miscanthus (Miscanthus spp.) survived the entire evaluation period in SRC, while two cultivars suffered losses only in LC, demonstrating the importance of site effects on the long-term performance of individual species or cultivars of grasses. Chalky bluestem (Andropogon capillipes) (Orange County, FL), sand lovegrass (Eragrostis trichoides), giant silver grass (Miscanthus ×giganteus), and bamboo muhly (Muhlenbergia dumosa) each survived 3 years at one site but only 1 year at the other site. Pineland threeawn (wiregrass) (Aristida stricta), ‘Red Baron’ cogon grass (japanese blood grass) (Imperata cylindrical), ‘Hameln’ fountain grass (Pennisetum alopecuroides), black flowering fountain grass (P. alopecuroides ‘Moudry’), and ‘Feesey Form’ ribbon grass (Phalaris arundinaceae) were categorized as marginal for low-input landscapes and could only be considered short-term perennials under the conditions of this test. ‘Morning Light’ silver grass (M. sinensis), coastal bluestem (Schizachyrium maritimum), and ‘Lometa’ indiangrass (Sorghastrum nutans) had good 2-year landscape performance and survived at least 2 years at both sites. Bigtop lovegrass (Eragrostis hirsuta), silver plumegrass (Saccharum alopecuroides), and lopsided indiangrass (Sorghastrum secundum) were categorized as having excellent 1-year landscape performance and have potential for short-term performance under low-input conditions. Chalky bluestem (Andropogon capillipes) (SRC), black flowering sedge, ‘Heavy Metal’ switchgrass (Panicum virgatum), and narrowleaf silkgrass were categorized as having good 1-year landscape performance.