Scored at 22 °C and 50% humidity, a moth orchid on a north sill comes back 98 out of 100, and a shelf a metre and a half in still reads 97. The light runs short between 1.5 and 2 m. Closer in, what moves the score is warmth: the same sill reads 98 at 21 °C and 68 at 20.
Read on 14 October 2026, the top results split over whether a north window is too dark. The American Orchid Society’s window article wouldn’t build an orchid sill there, though it wants any pot as close to the glass as it can sit. The society’s where-to-grow page calls north windows usually too dark, and Gardening Chores says too dark or cold. A 2011 TerraForums reply lets a moth orchid stay in one but doubts it will thrive. In the Philadelphia Inquirer, Longwood Gardens’ Greg Griffis ranks north the hardest window, where flowers often take a small grow light.
Too dark is true two metres into the room. On the sill the light is fine, and what costs this orchid points is a room at 20 °C, inside the temperature ranges two of those pages print.
Great fit
This plant should be happy in this spot.
Just the right amount of light
Comfortable temperature
Humidity suits it
Airflow suits it
Is a north-facing window enough light for an orchid?
First, what other sites print for an orchid’s light, each in its own unit:
| Who publishes it | What it says a orchid needs | What the figure is |
|---|---|---|
| growlightmeter.com | 4 – 8 PPFD / DLI | Orchid |
| staugorchidsociety.org | about 10,000 foot-candles | full sun equivalent, stated as too bright for most orchids |
| houseplantjournal.com | 200 FC (40 µmol) foot-candles | minimum indirect light level |
| houseplantjournal.com | 400 FC (80 µmol) foot-candles | good indirect light level |
| houseplantsnook.com | 100–200 foot-candles | chart fc level |
| soltech.com | 40+ PPFD / DLI | minimum fixture PPF to support flowering houseplants |
On the sill, yes. A clear-day north sill estimates at 3,640 lux, and the card above puts the light marker inside this orchid’s band, the same light verdict an east sill gets. Houseplant Journal’s minimum of 200 foot-candles, converted to lux, falls between our 1.5 m and 2 m rows below, which is where the score steps down. Its good level of 400 sits above our estimate for the sill.
So a north sill clears that minimum without reaching that source’s idea of good, and the flowering argument lives in the gap. Our score rates how well a spot suits the plant. It has no model of a flower spike, so it can’t say whether this orchid will rebloom on a north sill. A 1981 American Orchid Society Bulletin essay, reprinted by a local society, asks for a couple of hours of direct sun a day, with an exception for very bright sky light such as a tall north window. Window height isn’t one of our inputs.
How far from a north window can an orchid sit?
About a metre and a half, which is roughly five feet. The same pot, walked back from the glass:
| Distance from the glass | Estimated light | What the light is doing | Verdict |
|---|---|---|---|
| 0.3 m, against the glass | 3,640 lux | Just the right amount of light | Great fit, 98/100 |
| 1 m back | 2,800 lux | Just the right amount of light | Great fit, 98/100 |
| 1.5 m back | 2,222 lux | Just the right amount of light | Great fit, 97/100 |
| 2 m back | 1,764 lux | A little dim, but workable | Worth a try, 67/100 |
| 3 m back | 1,111 lux | A little dim, but workable | Worth a try, 64/100 |
| 4.5 m back | 556 lux | Too dim here | Not the best fit right now, 46/100 |
Between 1.5 and 2 m the estimate drops from 2,222 to 1,764 lux and the score from 97 to 67. After that the slide is slow, 64 at three metres, until 4.5 m back, where 556 lux is the first row the engine calls too dim. That row is what too dark looks like in our numbers. The keep-it-close advice is right, with more room than it lets on.
These lux figures are clear-day estimates from the window’s direction and the pot’s distance, not meter readings. A tree or a building across the street would bring the step nearer the glass.
Winter shortens the strip from the back. At latitude 40 the 1.5 m spot slips to worth a try from October to February while the sill holds all year, the same calendar a spider plant follows at this window, set out month by month on its own page. At latitude 51, roughly London, the sill itself slips to worth a try from November to January.
Is a north windowsill too cold for an orchid?
Often, and sooner than for most houseplants. Keep the pot on the sill, change only the air temperature, and watch which column moves:
| Air temperature at the sill | What the light is doing | What the warmth is doing | Verdict |
|---|---|---|---|
| 10 °C | Just the right amount of light | Too cold here | Not the best fit right now, 44/100 |
| 13 °C | Just the right amount of light | Too cold here | Not the best fit right now, 46/100 |
| 16 °C | Just the right amount of light | A little cool, but workable | Worth a try, 63/100 |
| 18 °C | Just the right amount of light | A little cool, but workable | Worth a try, 65/100 |
| 20 °C | Just the right amount of light | A little cool, but workable | Worth a try, 68/100 |
| 21 °C | Just the right amount of light | Comfortable temperature | Great fit, 98/100 |
The light column never moves. From 21 °C up, the sill is a great fit. At 20 the warmth reads a little cool and the score drops to 68, then 65 at 18 and 63 at 16. Under 16 °C, the minimum in the care data we score against, it reads too cold: 46 at 13 and 44 at 10.
That band starts higher than it does for the usual north-window plants. A pothos on this same sill stays a great fit down to 19 °C, and its page explains why a north pane runs cold after dark. The orchid’s trouble begins in a room most people would call comfortable. Gardening Chores gives 60 to 70 °F as a general orchid range, and in our scoring only the top of it, 70 °F or about 21 °C, makes a great fit. Griffis’s 55 °F floor lands next to our 13 °C row.
At 20 °C, no distance in the first table does better than worth a try. One degree warmer, the sill is back to 98.
Does an orchid need cold nights to rebloom?
Growers often say so. The 1981 essay says phalaenopsis answer the cooler nights of early autumn, in the 50s °F, by slowing their growth and then flowering. On our temperature table those nights are the two not-the-best-fit rows. Both hold up. The score measures how comfortable the plant is, and the essay describes a few weeks of discomfort used as a cue.
A north sill in October can supply those nights whether you planned them or not. What the table adds is the cost of leaving the pot there once the cue has done its work, since every row under 21 °C is worth a try at best.
Where should an orchid go in a north room?
On the sill or within a metre of it, in a room that stays at 21 °C or warmer by day. Dry winter air drags a moth orchid down in any room, and the east-window page walks that through. At a south window the problem flips: the sill is too bright, and the light flag only clears two metres back; at a west one only the midsummer sill is. The north window guide lists what else holds in this light, and the free spot checker scores your own sill with the weather where you live.
Published October 14, 2026
