Answer: Allamanda produces flowers on the current season's growth, so you'll want to prune in early spring to encourage a flush of flowering growth. There are several types of allamanda, which are either shrubs or vines:
Allamanda Brown Bud - Allamanda cathartica; Fast growing shrubbing vine that can reach 3-6 ft. in height. The stems of this plant can be pruned to keep this in bush form or let grow on a trellis to make a small vine. Produces LARGE yellow flowers that are brown before they open up. Blooms nearly year-round and is Very Showy.
Allamanda Bush - Allamanda neriifolia; Fast growing shrub that can get 3-5 ft. in height. Lush, dark green evergreen leaves that form a nice dense bush. Produces yellow trumpet shaped blossoms throughout the year. Great for hedges.
Allamanda 'Cherries Jubilee'; Fast growing vining shrub that can reach 3-6 ft. in height. Branches are long stems that can be pruned regularly to form a shrub or trellised to make a small vine. Produces a Striking Cherry/Lavander bloom, that can be as big as your hand, almost year-round. FULL SUN FOR BEST RESULTS.
Allamanda Dwarf - Allamanda cathartica 'Hendersonii"; Slow growing evergreen shrub that only gets 3 ft. in height. Small glossy green leaves form a nice tight shrub that creates a mounding shape. Produces yellow trumpet shaped flowers in the warmer months of the year. Protect from the cold.
Enjoy your garden!
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