Above-grade Planting with Organic Matter Improves Post-transplant Growth of Two Native Shrub Species

Abstract

Planting shrubs above-grade with organic matter has shown potential for improving landscape establishment. To further investigate this technique, wax myrtle [Morella cerifera (syn. Myrica cerifera)] (3 gal) and mountain laurel (Kalmia latifolia ‘Olympic Wedding’) (5 gal) were planted on 30 Oct. 2006 (fall planting) and 12 Apr. 2007 (spring planting) in the ground in a shade house in Auburn, AL. At each planting date, plants of each species were assigned one of four treatments. Three of four treatments used a modified above-grade planting technique in which shrubs were planted such that the top 3 inches of the root ball remained above soil grade. Organic matter, either pine bark (PB), peat (PT), or cotton gin compost (CGC), was applied around the above-grade portion of the root ball, tapering down from the top of the root ball to the ground. In the fourth treatment, plants were planted at-grade with no organic matter (NOM). In general, both species had higher shoot dry weight (SDW) and root spread (RS) when planted in the fall than when planted in spring. Among all treatments, plants also typically had larger RS when planted above-grade with PB or PT. For easy-to-transplant species (such as wax myrtle) and especially for difficult-to-transplant species like mountain laurel, fall planting using this modified above-grade planting technique with PB or PT may improve post-transplant root growth and speed establishment in the first growing season.