Below-Grade Planting Adversely Affects Survival and Growth of Tree Species from Five Different Families    (View PDF)

Michael A. Arnold, Garry V. McDonald, Donita L. Bryan, Geoffrey C. Denny, W. Todd Watson, and Leonardo Lombardini

Abstract: Adverse impacts of planting the root collar or main structural roots below grade on survival and growth were demonstrated for five species of container-grown trees from genetically diverse families. Adverse effects were demonstrated when root collars were located as little as 7.6 cm (3 in) below grade on all taxa tested, but severity of the responses varied among taxa. These responses were confirmed for both seed-propagated species, Fraxinus pennsylvanica Marsh. (green ash, family Oleaceae Hoffmansegg & Link) and Platanus occidentalis L. (sycamore, family Platanaceae Dumort.) as well as cutting-propagated taxa, Lagerstroemia indica L. × Lagerstroemia fauriei Koehne. ‘Basham’s Party Pink’ (crapemyrtle, family Lythraceae St.-Hilaire), Nerium oleander L. ‘Cranberry Cooler’ (oleander, family Apocynaceae Juss.), and Vitex agnus-castus L. ‘LeCompte’ (vitex, family Verbenaceae St.-Hilaire). In some cases, planting above grade by 7.6 cm (3 in) improved growth of plants over that of those planted either at or below grade. This effect was pronounced with sycamore and oleander.

Keywords: Apocynaceae; landscape installation; Lythraceae; Oleaceae; pine bark mulch; planting depth; Platanaceae; transplant establishment; tree planting; Verbenaceae

https://doi.org/10.48044/jauf.2007.008