Abstract

We investigated the performance of six Intermountain West (IMW) native herbaceous perennial species grown in a pot-in-pot (PIP) or conventional above-ground (CAG) production system for two years. Three different species were grown for two production cycles each year. Root zone temperature (RZT), plant and container water loss, stomatal conductance, plant height, and final biomass were measured. The RZT of plants in the PIP system were as much as 7C cooler than the CAG system, with temperature differences greater at the edge than at the center of the container. Water loss was approximately 10% lower for PIP plants on five of eight measured dates despite higher stomatal conductance on five of seven dates. Higher RZT and lower gas exchange reduced top growth more than root growth for CAG produced plants, but results varied with species and season. Conventional above-ground plants showed no visible damage but had slower growth rates compared to PIP plants. Lower elevation species were more tolerant of warmer above ground RZT, but more susceptible to winter damage. Results indicate that in areas with severe yearly temperature extremes, higher quality IMW herbaceous perennials could be grown with the PIP system in #1 containers compared to the CAG system.