Selenicereus validus S.Arias & U.Guzmán
Selenicereus validus is an attractive cactus with pendant, rope-like stems that branch at the base. The stems are green with very fine white spines, up to 16 inches (40 cm) long and up to 1.2 inches (3 cm) in diameter. Nocturnal flowers open in full darkness and stay open till late morning. They are up to 5 inches (22 cm) long, white and gold, and appear in warmer months.
USDA hardiness zones 10a to 11b: from 30 °F (−1.1 °C) to 45 °F (+7.2 °C).
How to Grow and Care
Perhaps the most important aspect of epiphytic cactus care is the potting soil. Experts are strongly divided on using commercial cacti or orchid mixes, but they agree that epiphytes need well-draining potting soil with lots of air space since the roots would naturally be exposed to air. If you wish to create your own mix, start with a basic formulation of 60 percent potting soil to 40 percent perlite. Other amendments are often added, including peat, orchid bark, sand, fine gravel, and leaf mold. Aim for a pH of 5.0 to 6.0 and plan to repot every 2 to 3 years if you use ingredients that eventually break down completely, such as orchid bark.
Epiphytes do not exist in the open sun, instead of receiving bright filtered light in most situations. They thrive as houseplants because of their relatively low light requirements. Ideally, you should provide full morning sun and shade for the rest of the day. An east-facing window with nothing blocking it can create these conditions. Light will affect the plant's willingness to bloom, though these requirements vary widely between epiphytes. Many can be coaxed into blooming by simulating short days by placing them in dark closets for 12 or more hours at a time for 4 to 6 weeks.
Learn more at Tips for Growing Epiphytic Cacti.
Selenicereus validus is native to southern Mexico.
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