Phalaenopsis orchids is likely where you began your orchid adventure, because they are everywhere and seem to forgive just about anything. They bloom month after month, forgotten on the kitchen counter; watered when remembered, scorched in the afternoon sun. And then…you get curious.
You find a Vanda (those amazing aerial roots!), or maybe a Cattleya (so dramatic!) and bring one home. Now what? You stick her alongside moth orchid, and then what happens? The foliage darken and droops. It never bloom. What gives?
How to Give Your Orchids the Right Light
Well, all that magic? Not really… It’s just physics. Every bloom start with light as its engine, and unless you provide the right level to the right species, it’s like asking your plant to jog a marathon in a pair of winter boots.
Light can be broken into cardinal directions. That’s how I’ve listed it out in the visual guide (above). This is far more useful than a chart of abstract numbers. In most houses, we are dealing with little window space. Knowing what an east or south facing window delivers, different than a north- or west-facing one, is more valuable than knowing foot-candles.
For example, diffuse, cool light from a north-facing window is never harsh. This is great for growing Paphiopedilum (or other “slipper” orchid). Their ancestors grew on the shaded forest floor of Southeast Asia, so direct sun will literal cook them. Stick a Phalaenopsis in there instead, however, and it will remain green and content as a clam, but never bloom. That’s the pitfall. You’re keeping the plant alive, sure, but you aren’t encouraging it to thrive; it doesn’t have reserves of energy to devote to reproduction, because it’s just enough photosynthesizing to meet its own metabolic needs.
Move up to the east window, though, and you’re looking at gentler morning sun with cooling afternoon hours. That’s the “sweet” spot for most first-time orchid grower: Not too hot, not too cold; good lighting without burning your face off (meaning no curtains usually needed). It is consistent, forgiving, and reliable.
Move farther on to south and west exposures, and you’re getting into higher-light territory. Blazingly hot direct sun from a south window will burn foliage in minutes come high summer. This is an ideal habitat for high-light species such as Vanda and Cymbidium, which want full exposure to match their origins in the tropical forest canopy.
The chart above say these are the ones whose bronzey leaves quickly turn burned if they spend even an hour of high summer outdoors without shade cloth. It is easier to read your orchid’s leaves than to purchase equipment. Not enough light? Dark, deep green usually signal insufficient light. To capture every stray bit of light, the plant will pump out an excess of chlorophyll, lush growth, zero flowers. Sun-stressed? Yellow-tinged (or reddish) leaves are the sign. As a sunscreen, the plant makes compounds called anthocyanins.
Neither is good. What you seek: bright, medium lime-green, indicating the plant is comfortable and metabolically active.
Does it look toasty? Pull back, or insert a sheer layer of something between the soil and the sun. It looks moss-like on the forest floor. Get it closer to the glass. As seasons change, the needs changes and I am constantly adjusting. In winter, days are shorter and the light is weaker. Because of this, even sun-filled south windows lacks enough energy for blooms. That’s where supplemental LED lights comes in…to bridge the gap and maintain activity on short days rather than replacing sunlight. In summer, it’s time to protect from heat (root-drying), with some sort of shade curtain or cloth to prevent sunburn.
There is a fine line between too hot and too cool, and again it’s about inches at a time. It is about temperature and light. So begin not with “I want an orchid,” but rather with “Where is my window?” If it’s north, limit yourself to low-light types. If it’s blisteringly sunny south, go for the high-light types. Rotate the pots each week so plants grows evenly. Observe the foliage: That’s how they’ll tell you their desires (long before the flowers).