Abstract

Many western native plant species occur in areas characterized by well-drained soils low in organic matter. Some drought-tolerant native plant species exhibit poor seed germination. It was hypothesized that traditional growing substrates high in organic matter may impede their germination; therefore, stratified seeds of roundleaf buffaloberry (Shepherdia rotundifolia) and silver buffaloberry (Shepherdia argentea) were sown in three substrates differing in organic matter and drainage properties. Seed flats were irrigated twice daily to container capacity, and held on a greenhouse bench for 40 days. Seeds of roundleaf buffaloberry exhibited greatest total germination in a calcined montmorillonite calcined clay substrate (66%); seeds exhibited low germination in a commercial peat-based germination mix (13%) and in a self-prepared, locally popular substrate (22%) that contained sphagnum peat: perlite: calcined clay: sand (2: 2: 1: 1 by vol). Seed germination of silver buffaloberry varied from 42 to 54% and was not different among the three substrates. When substrates are kept consistently moist, a calcined-clay substrate can improve germination of roundleaf buffaloberry, but not silver buffaloberry.