Plants for a north-facing window

A north-facing window (in the Northern Hemisphere) never looks at the sun’s path across the southern sky. What it gets is skylight: light scattered by the sky and clouds, plus whatever bounces off the ground and buildings outside. That makes it the gentlest window in the house, and also the dimmest.

Extension services agree on the broad picture. Illinois Extension puts the spot directly in front of a north window at medium light (about 150 foot-candles) and “a few feet away” at low light (75 foot-candles). UF/IFAS notes that even in winter, when outdoor light at noon can top 4,000 foot-candles, a north window “may never reach even 400”. Clemson suggests north exposures for low-light plants such as peace lily, heart-leaf philodendron and cast-iron plant.

Why north light is steady but dim

Because a north window sees only sky, its light changes less from hour to hour and from sunny day to cloudy day than an east, west or south window does. Our planner shows this clearly. For a north window in New York (40.7°N), double-pane clear glass, open sky and a “mixed” climate, its estimate for a leaf 1 ft (0.3 m) back is almost the same in a dull month as in a bright one. In June, for example, the duller setting actually gives slightly more (about 8.8 vs 7.9 mol/m²/day), because a hazier sky spreads more light into the north half of the sky.

Steady is not the same as bright, though. With those same assumptions, our planner estimates (typical values):

Month	1 ft (0.3 m) from glass	4 ft (1.2 m) from glass
December	2.7 mol/m²/day	0.95 mol/m²/day
March	5.4	1.9
June	8.3	3.0
September	5.9	2.1

For comparison, Iowa State Extension’s classes for indoor plants are 3 to 6 mol/m²/day for low light, 6 to 10 for medium and 12 to 16 for high light. So at 1 ft, a New York north window clears the medium-light growth level from April to August and the low-light level in every month except December and January. The chart below shows the full year at both distances.

Distance matters more than anything else

The 4 ft column above is the most important number on this page. Moving a plant from 1 ft to 4 ft back cuts its light to roughly a third, in every month. At 4 ft our planner never reaches the low-light growth level (3 mol/m²/day) at all; the best month, June, tops out just under it.

The reason is geometry. A leaf right at the glass “sees” a large slice of sky. A few feet back, the window frame shrinks that slice to a small patch, and the rest of what the leaf sees is wall and ceiling. Maryland Extension puts it simply: light intensity “decreases rapidly with increasing distance”.

In practice that means a north window is a windowsill or a plant stand pushed against the glass, not a corner across the room.

Reflections help a little

Maryland Extension notes that light-colored, reflective surfaces in the room raise ambient light, and Clemson lists wall color among the things that change how much light a spot gets. Outside, a pale wall or building across the street sends some light back toward your window. Our planner assumes the ground and any buildings in view reflect 20% of the light that falls on them, a conservative middle value, so a bright courtyard could do somewhat better than its estimate. Dirty glass, screens and curtains all work the other way; Maryland lists all three as things that cut indoor light.

Summer sun on north glass

North windows do get some direct sun at mid and high northern latitudes. Between the spring and autumn equinoxes the sun rises north of due east and sets north of due west, and FAO’s day-length tables show why it matters: at 40°N the June day is about 14.6 hours long, so there is a long stretch of early-morning and evening sun in the northern sky.

Our planner puts direct sun on the glass of a New York north window from April to August, peaking at roughly 5 to 6 hours a day in June. But that sun arrives low and at a sharp sideways angle to the glass. In a standard 3 x 4 ft window, the planner finds none of it reaching a leaf 1 ft back from the middle of the window. Treat it as a small summer bonus for plants right on the sill, not as “a few hours of sun”.

Plants that suit a north window

The table below lists the plants in our database that our planner rates as “thrives” or “winter dip” at 1 ft from a New York north window (same assumptions as above), plus those it rates “survives” that extension sources say cope with low light. Read the verdicts carefully:

• Cast iron plant is the only one rated “winter dip”: it reaches its low-light growth level in every month except December and January.
• Medium-light plants such as Chinese evergreen, snake plant, peace lily, calathea, prayer plant and kentia palm are rated “survives”: they reach their growth level from April to August and hold on, growing slowly, the rest of the year. NC State specifically names a north window as suitable for Chinese evergreen, and suggests a north- or east-facing window for parlor palm.
• Plants that want bright light and don’t tolerate low light are left out. The planner rates most of them “survives” at best here, because they never reach their ideal level at this window: expect slow, stretched growth if you try.
• Sun lovers such as basil and rosemary are rated too dim.

Pet owners: cast iron plant, calathea, prayer plant, kentia palm and parlor palm are listed as non-toxic to cats and dogs by the ASPCA. Chinese evergreen, peace lily and heartleaf philodendron contain insoluble calcium oxalates, and snake plant contains saponins; all four are listed as toxic to cats and dogs. If a pet eats a plant, call your vet or the ASPCA Animal Poison Control Center at (888) 426-4435 (24/7, a consultation fee may apply). This guide is not veterinary advice; the pet-safe plant checker has the full ASPCA details for each plant.

In the Southern Hemisphere, flip it

South of the equator the sun crosses the northern sky, so everything above applies to a south-facing window instead. Our planner shows the swap: for Sydney (33.9°S), a south window 1 ft back follows the same pattern as a New York north window, dropping to about 3.3 mol/m²/day in June, while a north window stays near 9 all year.

Check your own window

Your city, glass, distance and view change these numbers. Enter them in the Window Light Planner to get your own month-by-month estimate and plant list (how it works). If winter light is the problem, see how much light houseplants lose in winter and how far a grow light should be from plants.