Effects of Transplant Season and Container Size on Landscape Establishment of Kalmia latifolia L.

Abstract

<jats:p>Mountain laurel (<jats:italic>Kalmia latifolia</jats:italic> L.) is a common native shrub in the Eastern United States; however, this species can be difficult to establish in landscapes. Two experiments were conducted to test the effects of transplant season and container size on landscape establishment of <jats:italic>Kalmia latifolia</jats:italic> L. `Olympic Wedding'. In experiment one, 7.6-L (2-gal.) and 19-L (5-gal.) container-grown plants were planted into a simulated landscape (Blacksburg, Va., USDA plant hardiness zone 6A) in early Fall 2000 and in late Spring 2001. 19-L (5-gal.) plants had the lowest leaf xylem potential (more stressed) near the end of the first post-transplant growing season, and leaf dry weight and area were higher for spring transplants than for fall transplants. For spring transplants, 7.6-L (2-gal.) plants had the highest visual ratings, but 19-L (5-gal.) plants had the highest visual ratings for fall transplants three growing seasons after transplanting. 7.6-L (2-gal.) plants had the highest % canopy volume increase after three post-transplant growing seasons. In experiment two, 19-L (5-gal.) plants were transplanted into above-ground root observation chambers (rhizotrons) in early Fall 2000 and late Spring 2001. Roots of fall transplants grew further into the backfill than spring transplants at the end of one post-transplant growing season. Overall, our data suggest that smaller plants will be less stressed the first season after transplanting and will likely stand a better chance for successful establishment in a hot and dry environment. Fall is the preferred time to transplant since capacity for maximum root extension into the backfill will be greater than for spring transplants.</jats:p>