Fertilizer and container requirements of Balsamorhiza sagittata and Phacelia hastata var. hastata under greenhouse production

Abstract

Arrowleaf balsamroot (Balsamorhiza sagittata (Pursh) Nutt. [Asteraceae]) and silverleaf phacelia (Phacelia hastata Douglas ex Lehm. var. hastata [Hydrophyllaceae]) are Intermountain West native plants with potential horticultural uses in native and low-water-use landscapes; however, information is lacking on greenhouse production. This research focuses on the container type and fertilizer rate necessary for greenhouse production. Seedlings were transplanted into 10-cm (4-in) square pots or cone-shaped containers and fertilized at 5 rates, once a week. For arrowleaf, rates of 200 and 400 mg/l of nitrogen (N) resulted in the highest shoot dry weight, leaf width, and leaf length measurements, whereas the root-to-shoot ratio declined when more than 100 mg/l N was applied. Cone-shaped containers proved to be a more effective container type for arrowleaf balsamroot production, based on root morphology, root dry weight, and leaf width response. For silverleaf phacelia, shoot dry weight, plant height, and canopy diameter increased as fertilizer rate increased from 50 to 200 mg/l N, whereas the root-to-shoot ratio declined if more than 50 mg/l N was applied. The 10-cm square pot was superior to the cone-shaped container for silverleaf phacelia, based on much higher shoot and root dry weights and on plant height and spread.