The narrow-leaved, slender-stemmed Madagascar dragon tree (Dracaena marginata) is far too delicate to bear such a ferocious common name. Most widely used as a tropical indoor accent plant, dragon tree grows outdoors only in the balmy climates of U.S. Department of Agriculture plant hardiness zones 10 through 12. Indoors or outdoors, it's a relatively undemanding plant seldom bothered by pests or diseases.
Characteristics and Cultivars
Growing up to 20 feet tall outdoors and 6 to 10 feet tall as an indoor plant, dragon tree has narrow, erect gray-barked stems. Rapier-thin, red-margined green leaves drop from the plant as they age, leaving only arching tufts of the glossy foliage to crown the stems. Outdoor plants produce dainty, fragrant white spring flowers and orange fall berries. Creamy-yellow stripes line the red edges of the dragon tree cultivar "Tricolor's" (Dracaena marginata "Tricolor") green leaves. Red striping nearly obscures "Colorama's" (Dracaena marginata "Colorama") light green foliage.
As a houseplant, dragon tree does best in a well-draining mixture of peat moss and sterilized loamy garden soil. University of Illinois Extension recommends 3:2:2 ratio of peat, soil and vermiculite. Keep the plant in a draft-free, bright spot out of direct sun at temperatures between 65 and 75 degrees Fahrenheit. Water as needed with fluoride-free water to keep the soil consistently moist, never soggy. From early spring through late summer, replace two watering sessions per month with applications of water-soluble 20-20-20 houseplant fertilizer. Mix 1/2 teaspoon, or the label's recommended amount, of the fertilizer in 1 gallon of water and pour it evenly around the dragon tree. Cut back to one monthly application in fall and winter.
Outdoor dragon tree tolerates shade, but has more vivid color with some sun. It needs moist, well-draining soil rich in organic matter. For the densest foliage, periodically prune its stems as the plant becomes taller. It produces two new branches from each pruned one. To avoid spreading disease, disinfect your pruning tools by dipping them in rubbing alcohol between cuts. Watch for occasional infestations of spider mites -- tiny insects that spin fine webs on the foliage -- or sap-sucking scale insects that cover the plants with sticky, clear waste. These pests also attack indoor dragon trees. Scrape scales off with a soft toothbrush and dislodge spider mites with a strong spray of water.
The Dragon Tree Drawback
The major drawback to growing dragon tree is its toxic effect on cats and dogs. The American Society for the Prevention of Cruelty to Animals reports a variety of symptoms in pets eating the tree's unidentified toxins. They include vomiting, loss of appetite, weakness, drooling and loss of coordination. Affected cats may also have dilated pupils, digestive pain and elevated heart rate. Keep your indoor dragon trees where the pets can't reach them, and supervise the pets when they're around your outdoor ones.