Hylocereus undatus, commonly known as night-blooming cereus or Christ in a manger plant, is a fast-growing vine from the cactus family. Originating in the tropics, this plant produces long, slender stems in yellow or light green. Flowers develop along these stems, reaching up to 12 inches in diameter and opening only during the night, beginning around 9 or 10 p.m. This fruit-producing plant is easy to grow, according to University of Arkansas Cooperative Extension Service.
Keep the Christ in a manger plant as a houseplant, except in the summer, when it will flourish outdoors in an area with filtered light. Protect it from direct sunlight, however, especially in the afternoon. Plant the Christ in a manger plant outdoors in tropical or subtropical climates free of frost. Temperatures over 100 degrees Fahrenheit may damage the plant, according to University of Florida Extension.
Plant the Christ in a manger plant in well-drained, nutrient-rich soil. This member of the cactus family grows best in sand-based soils. Mix sand and potting soil together and place in a container for an optimal potting medium. Leave new plant cuttings in a pot for at least four months to develop a strong root system before transplanting outdoors.
For indoor Christ in a manger plants, fertilize monthly with a water-soluble fertilizer. Outdoor plants benefit from an annual application of organic material, such as manure. Apply 4 pounds around the base of the plant, gradually increasing the amount to 6 pounds over the first four years. Use a balanced fertilizer every other month, and add iron to soil with a neutral or low pH level.
The Christ in a manger plant withstands drought well, but requires regular irrigation followed by a dry period for the best growth and bloom production. Keep soil moist throughout the spring and summer months, but remember that cactus plants require less water than other houseplants, warns University of Arkansas Cooperative Extension.
Allow soil to dry out completely between waterings during the fall and winter months. Stop fertilization during this time as well. Avoid frequent repotting, as this plant blooms best when rootbound. Slowly increase watering as spring begins.