Evaluation of Plant Growth and Flowering Performance of Florida Native and Non-native Ornamentals under Varying Irrigation
Authors: Silva Joanna J. , Wilson Sandra B. , Knox Gary W. , Mallinger Rachel E. 
Published: September 2024

Pollinator gardening has gained momentum with an increased consumer interest in selecting native rather than non-native plant species to reduce water dependence and maximize the biodiversity value in both public greenspaces and residential gardens. Native plant species can enhance biological control and benefit ecosystems and wildlife. Often, they are also better-adapted to local environmental conditions, including temperature and rainfall, thus increasing their survival and reducing associated maintenance costs, primarily by requiring less water. Commercially available pollinator-friendly plant mixes often include both native and non-native species. A 2-year study was conducted to determine the main effects of plant provenance (native or non-native) and irrigation (full or partial irrigation) on landscape performance and flowering of 20 plants, including 10 congeneric pairs of native and non-native taxa that were planted in two locations (north and northcentral Florida). Native and non-native taxa were paired by genus to analyze the effect of the plant native status on vegetative and floral traits while controlling for variations in leaf and floral morphologies, growth habits, and blooming periods, which was a key and novel component of our study design. Represented native species included Spanish needles (Bidens alba), false rosemary (Conradina grandiflora), tickseed coreopsis (Coreopsis leavenworthii), blanket-flower (Gaillardia pulchella), swamp rosemallow (Hibiscus grandiflorus), inkberry (Ilex glabra), spotted beebalm (Monarda punctata), azure blue sage (Salvia azurea), Florida scrub skullcap (Scutellaria arenicola), and Walter's viburnum (Viburnum obovatum). Non-native taxa paired with native congeners included Beedance® painted red bidens (Bidens ferulifolia) or Goldilocks Rocks® bidens (Bidens ferulifolia ‘BID 16101’), barbeque rosemary (Salvia rosmarinus ‘Barbeque’), Jethro Tull coreopsis (Coreopsis × ‘Jethro Tull’), Arizona sun blanket-flower (Gaillardia ×grandiflora ‘Arizona Sun’), Ruffled Satin® rose of Sharon (Hibiscus syriacus ‘SHIMCR1’), dwarf Burford holly (Ilex cornuta ‘Dwarf Burford’), pardon my pink beebalm (Monarda didyma ‘Pardon My Pink’), big blue salvia (Salvia longispicata × S. farinacea ‘PAS1246577’), Malaysian skullcap (Scutellaria javanica), and Sandankwa viburnum (Viburnum suspensum). Overall, the results revealed that native plants outperformed non-native plants and exhibited greater survival, more vegetative growth, and greater floral abundance regardless of the irrigation treatment. Although there was no overall effect of irrigation on plant size or flower abundance, there were some species-specific responses, especially during the establishment year, and plants under full irrigation had greater survival in the establishment year. Thus, in general, the effects of plant provenance were stronger and more consistent across years than irrigation. Additional studies are underway to determine the floral rewards of these species and their attraction to diverse pollinators.