Growth characteristics and post trimming regrowth potential of tropical and sub-tropical landscape hedge plants in response to spacing

Abstract

Spacing of landscape plants is one of the factors determining the outcome of a design in terms of canopy formation which is one of the variables for aesthetic appearance in terms of shapes and forms. This study was conducted between September 2016 and September 2017, to determine the appropriate intra-row spacing for five plant species in hedge formation. The plant species used were Duranta erecta, Hamelia patens, Ficus retusa, Buxus sempervirens and Acalypha wilkesiana. Transplanting was done at intra-row spacing of 30, 40, 50 and 60cm and a constant inter-row spacing of 100cm. The experiment was a Randomized Complete Block Design in split plot arrangement with three replicates. Plant height, number of leaves, number of branches and canopy space, as indices of species suitability for use as hedge, were measured fortnightly. Plant regrowth and aesthetic characteristics were assessed after periodic trimming. H. patens and B. sempervirens species had the tallest plants. B. sempervirens and D. erecta produced the highest number of leaves while D. erecta and H. patens had the highest number of branches. D. erecta had significantly (p<0.05) the fastest post-trimming shoot regrowth rate relative to other species following the 1st and 2nd trimming (25 and 28 WAT respectively). The effect of spacing on shoot regrowth length was significant after the 3rd, 4th and 5th trimmings (31, 34 and 37 WAT respectively). The highest shoot regrowth height was recorded at 40cm spacing followed by 30cm intra row spacing. All species responded best at 50cm intra-row spacing for the number of branches and canopy space as well as early hedge formation. The study concluded that B. sempervirens was suitable for ideal hedging at 40cm intra-row spacing while A. wilkiesiana and H. patens were only suitable as informal hedges. Hence, B. sempervirens species is recommended as the ideal hedge plant choice based on its early regrowth after trimming, high leaf and branch production as well as overall speed in hedge formation at 31WAT.