Orchid advice from Jim Marlow

Oncidium orchid Sharry Baby courtesy kaiyanwong223 / Flickr

This is the full text of an article I published in the Democrat and Chronicle in February of 2011. Due to some inquiries on facebook I am posting it here. -- Jane

“Light is really the most important factor.”

I recently visited orchid man Jim Marlow at his greenhouse in Scottsville, and this was the very first thing he impressed upon me about orchid care. You can mess around some with temperature and other variables, but if your orchid won’t bloom, chances are it’s not getting the correct light.

The phalenopsis, or moth orchid, is considered the easiest to grow, in part because it is among those that require the least light—about 1500 candles. On a sunny day at around noon, hold your hand about 12 inches above the orchid. If you see a fuzzy shadow, you have around 1500 foot candles. According to Marlow, that would be set back a little way from an east or a south window, or a little farther back from a west window. This position, or even a little less light, would also work for the slipper orchid, paphiopedilum.

Oncidiums can take a little more light, directly in an east or south window or set back from a western exposure. Cattyleas want a little more, and cymbidium a little more than that. Vandas need to be in a greenhouse, under bright artificial lights or outdoors (in summer). (Vandas also like to be watered every day.)

You can tell if your orchids are getting enough light by the leaves. It’s counterintuitive, but dark green leaves are not good. You want more of a lime green color.

Orchids also have varying temperature requirements, though for the most part, they enjoy a ten degree—or more—swing between day and night. Cymbidiums require cool temps, down to 45 or 50 degrees at night, in the fall, in order to set buds, which is perfect for our climate—just leave them outside until it gets any colder than that. Like all houseplants, orchids benefit from summering outside. Just watch that they don’t get too much sun, and keep them off the ground.

Intermediate temperatures are considered 55 or 60 degrees at night, which is about right if you live in an old house like I do. That factor, plus a good window in the dining room, is what prompted me to risk a couple of oncidiums from Marlow’s place. Fingers crossed.

A warmer home, with night temperatures around 65 degrees, is perfect for phalenopsis and certain paphiopedilum.

There is a huge amount of orchid growing information out there, much of it conflicting. Just jump in, says Marlow, and you’ll start to pick up a knack for what they need. The key is to try new things. If a particular plant isn’t thriving the way you’d like, move it. “Growing orchids—growing anything—is an experiment.”