Allamandas (Allamanda spp.) are frost-sensitive Brazilian natives suitable in outdoor gardens in U.S. Department of Agriculture hardiness zones 9 through 11. In cooler areas, allamandas are grown as annuals and brought indoors in containers for winter protection. Depending on the cultivar, the plants grow as bushes or vines. The twining vine Allamanda cathartica can be shrub-like with pruning, while Allamanda neriifolia is a shrub. Both are hardy in USDA zones 9 through 11. Plants have dark to light green foliage and produce masses of yellow, trumpet-like blooms. They brighten dull landscape locations, patios or pool areas.
Use a 3- to 5-gallon container for growing allamanda. This is large enough to allow proper root spreading. Select a container with bottom drainage, as plants will die in containers that retain water.
Mix a slow-release fertilizer into a well-draining potting mix that fills the container. Follow your product's directions. For example, mix 1 tablespoon of a 15-15-15 slow-release granular fertilizer in a 5-gallon pot. The fertilizer slowly disintegrates into the soil and nourishes the roots for approximately three months.
Fill the container one-third full of the potting mix. Remove the plant from its nursery container and gently pull apart wrapping roots with your hands. Place the allamanda inside the container and finishing filling the pot with soil, firming the soil around the root ball with your hands. Plant the allamanda no deeper than it was originally growing in the nursery pot.
Water the allamanda after planting, letting water run from the bottom drain holes. Water plants regularly, whenever the soil feels dry. Containerized soil dries out quickly, especially in warm weather. Allamanda plants prefer moist, well-drained soil conditions. Situate the container in full to partial sun. In areas with hot suns, give the plant filtered shade in early afternoon.
Prune to control the plant's size and shape. Use sharp pruning shears and trim freely. To prevent spreading disease, sterilize your pruner blades with household disinfectant before and after your pruning session. Pruned allamandas grow thicker.
Clear all weeds from a planting site located in full to partial sun with well-draining soil. Remove the vegetation by hand weeding, shoveling and raking the area, or by killing the vegetation beforehand by covering it with black plastic until the weeds and grasses die. Allamandas in sunny locations produce more flowers.
Dig a hole twice as large as the allamanda's root ball. Remove the allamanda from the nursery container, and pull apart any wrapping roots. Place it into the hole and backfill the hole with soil, firming it around the root ball with your hands. Planting allamanda no deeper than it was originally growing.
Plant vine-like allamandas approximately 1 foot in front of a wall, arbor, fence or trellis. This gives the plant enough room to spread and climb up the structure. Water the allamanda after planting, saturating the roots. Apply water regularly to keep the soil moist, but not soggy. Water it thoroughly when you water, then let the top of the soil dry slightly before you water again.
Fertilize monthly with a balanced, all-purpose, water-soluble fertilizer. For example, mix 1 tablespoon of water-soluble 10-10-10 fertilizer with 1 gallon of water, and water in. Prune allamanda as necessary to control its shape and size, in the same manner used to prune container plants.