"Crimson Star" adenium (Adenium obesum "Crimson Star") displays intense red flowers and stout, upright stems atop swollen, twisted, partially buried roots. This tough desert plant is a succulent, storing water that sustains it through extended dry periods. You can grow the interesting-looking "Crimson Star" in the ground or in containers. It does best outdoors, where it is perennial in U.S. Department of Agriculture plant hardiness zones 11 through 12. In cooler climates, bring the plant indoors when temperatures drop in autumn.
Place "Crimson Star" in bright sunlight, because the plant becomes tall and spindly in shade. However, if you live in a hot desert climate, your adenium will benefit from partial afternoon shade.
Water "Crimson Star" whenever the top 1 to 2 inches of soil feel dry to the touch. Never water if potting soil still feels moist from the previous watering. For potted adenium, drench the potting mixture until water trickles through the drainage hole to be sure the entire soil mass is wet, then let the pot drain thoroughly.
Fertilize the plant once every month during spring and summer, using a general-purpose, water-soluble fertilizer mixed at half-strength -- about 1/4 teaspoon per gallon of water. Withhold fertilizer during fall and winter.
Bring Crimson Star" indoors before nighttime temperatures drop below 50 degrees Fahrenheit. Place the plant in a warm room and the brightest possible light -- usually a south- or west-facing window. Be sure temperatures remain above 50 degrees, otherwise the plant may enter dormancy.
Continue to water the plant during the winter, but be sure the potting mixture becomes almost completely dry between waterings.
Move the plant outdoors and resume normal water and fertilization after all frost danger has passed in the spring.
Prune the plant once every year between late winter and early autumn, if needed. Remove branch tips to create a fuller, bushier plant, or prune several inches to remedy a leggy, overgrown plant. Make each cut just above the leaves and avoid pruning bare stems low on the plant.
Spray "Crimson Star" with insecticidal soap spray if the plant is bothered by sap-sucking pests such as aphids, spider mites or mealybugs. Mix commercial spray at a rate of 5 tablespoons in 1 gallon of water. Coat the plant thoroughly, including both sides of the leaves. Repeat as needed every four to seven days.