Seed Germination and Growth Requirements of Selected Wildflower Species

Abstract

The effect of imbibition, funcigidal pre-treatments, and stratification time length on seed germination of Rudbeckia fulgida Aiton (orange coneflower), Penstemon laevigatus Aiton (eastern smooth beardtongue), and Lobelia cardinalis L. (cardinal flower) was studied. Seeds were either imbibed or not imbibed (before stratification), treated with fungicide or not, (after stratification), and stratified at 5±1°C (41°F) 3 or 6 weeks, or not stratified, and then placed in germination chambers set at 30±1°C. Each experiment was repeated for a total of three runs per species. Germination of R. fulgida was highest when seeds were imbibed and not stratified. Germination of P. laevigatus was higher when seeds were imbibed and stratified at 5°C (41°F) for 6 weeks. Germination for L. cardinalis was negligible, regardless of treatment. Seeds of Coreopsis tinctoria Nutt. (golden tickseed), Coreopsis verticillata L. (whorled tickseed), Echinacea purpurea (L.) Moench (eastern purple coneflower), Gaillardia pulchella Foug. (firewheel), and Rudbeckia hirta L. (black-eyed Susan) were sown in three Alabama soil types at four sowing depths. For R. hirta and C. tinctoria, survival and subsequent growth were higher when seeds were surface sown than when sown below the surface. For G. pulchella and E. purpurea, survival and subsequent growth were highest when seeds were sown below the surface. Soil type influenced survival and subsequent growth of all species. There was higher survival and subsequent growth when seeds were sown in Wickham sandy loam and Marvyn loamy sand than when sown in Houston clay. Poorer germination in the Houston clay was likely due to the higher clay content of the soil, which retained water for a long period, causing seed and seedling rot.