Native to Reunion Island, Marginata or the Madagascar dragon tree (Dracaena marginata) grows 6 to 15 feet tall and produces tiny white flowers and golden yellow berries in summer. Popular as a house or office potted plant, its grass-like leaves are deep green and soft. More colorful leaved selections, with white, green and rosy pink hues include 'Tricolor' and 'Colorama'. It grows outdoors in USDA Hardiness Zones 10 and warmer.
In tropical regions, Marginata grows strongly in full sun exposures, receiving more than 8 hours of direct sun rays daily. It tolerates lower light conditions, such as dappled shaded under larger evergreen trees, but varieties with white and pink colored leaves lose their intensity if light levels drop too low. As an interior potted plant, Marginata needs very bright, indirect light but also tolerates as much direct sunlight near a window as possible to promote a good cluster of leaves atop each stem. Too little light indoors results in lower leaves in stem clusters to drop away and new growth to be sparse.
Outdoors plant Marginata in a sand or loam soil that comprises a lot of organic matter so that the soil remains evenly moist but well-draining. Avoid alkaline soils and heavy clay that compacts and remains soggy after rain or irrigation. Top-dress the root zone with organic mulch to a depth of 2 to 4 inches. Interior specimens also need a moist, well-draining soil and the typical peat-based potting mix suffices.
From spring to fall, water Marginata freely in the outdoor tropical garden and reduce watering to mimic a natural seasonal winter dry spell. Increased ambient humidity in summer benefits the plant and can coax flowering. Apply granular, well-balanced fertilizers or compost in spring and summer according to product label directions.
Marginata plants respond poorly to municipal water that contains fluoride, especially when grown as potted plants. Never overwater interior plants since they receive lower light levels and remain in comparatively cooler and drier air. When the top inch of potting soil feels slightly dry to the touch, add water. Use liquid fertilizer in a dilute solution as part of the spring or summer watering schedule, but never fertilize in fall or winter.
While older plants naturally branch to create more rounded, V-shaped large shrubs or small trees, leggy stems can be pruned back severely in spring. Dormant buds sprout from below the pruning cut and form new foliage tufts. Consider thinning out masses of stems that regenerate after a pruning so only two or three branches remain. Drooping lower leaves snap off from the stem relatively easily and keeps the plant looking tidy, especially if they become yellowed or riddled with dry brown edges.
Outdoor grown Marginata plants suffer few problems. Indoor plants may succumb to bouts with spider mites, scale or mealybugs. In warm, dry-air environments spider mites tend to be the primary pests and can be diminished by hosing off leaf undersides. Scale and mealybugs must be wiped off with a damp cloth soaked in warm, lightly soaped water. Squishing bugs works, too.