Dragon fruit, or night blooming cereus (Hylocereus undatus), is both a valuable outdoor fruit crop plant and a fascinating houseplant. Despite its plain Jane appearance, dragon fruit, a member of the cactus family, produces stunningly beautiful and exotically scented flowers. The plant has slim, spiny stems along which the flowers bloom in late summer. Up to 12 inches wide, the white, funnel-shaped flowers open at night and last only one night. The blooms open so quickly you can see them moving, and the scent of a single flower can perfume an entire room.
Potting mixes for indoor dragon fruit plants must have excellent drainage properties. Check the label on the potting soil to make sure it is an appropriate mixture for cacti. Many commercial potting soil mixes for cacti contain sand, perlite or vermiculite, plus organic matter such as bark. Perlite improves drainage better than vermiculite. The sand should be coarse-textured and may be labeled "horticultural grade" or "washed." Look for a mix that includes bone meal, which helps promote good flowering
As the name implies, potting mixes labeled "soilless" contain no soil at all. This type of growing medium usually has reduced porosity and is formulated for maximum moisture retention. Unless the mixture is specifically formulated for cacti, do not use soilless mixtures for dragon fruit plants, because too much moisture in the growing medium invites root rot.
Make Your Own
Making your own, semi-homemade potting mixture for dragon fruit is not difficult, but may actually be more expensive than purchasing commercial cactus mixes. Mix four parts all-purpose potting soil with five parts perlite and one part coarse sand. Add a pinch of rock dust. Use washed builder's sand or #12 silica sand, not sandbox or playground sand.
Another "recipe" calls for mixing three parts potting soil with one part sand. If the plant is in a pot with poor drainage, mix the potting soil half and half with the sand for faster drainage.
Using Potting Mixtures
Moisten the potting medium before planting the dragon fruit. Add one part vinegar to five parts water to increase the medium's acidity level. Allow the potting soil to dry out between waterings during fall and winter, when the plant is not actively growing. This also helps the plant bloom next year. Remember that cacti need less water than other houseplants. Dragon fruit do not mind being slightly potbound and do not need repotting often.