Light: a Quebec room for a plant that grew in Thailand

Every care label says bright indirect light. None of them say what that looks like in a Montréal flat in November. Light decides whether a plant grows or merely survives, and it is the single biggest difference between where our plants come from and where they end up.

A test that takes five seconds

At the brightest part of the day, hold your hand a foot above where the plant will stand and look at the shadow.

• A sharp, dark shadow — direct light. Fine for cacti, too much for aroids.
• A soft shadow with clear edges — bright indirect. This is what nearly everything we import wants.
• A faint blur — low light. A Sansevieria will cope; a variegated Monstera will not.
• No shadow — too dark for a living plant, whatever the label promised.

Distance matters more than direction

Light falls away far faster than it looks. A spot two metres back from the window receives a fraction of what a spot beside it does, though both feel bright to you — your eye adjusts, a leaf cannot. When a plant is not thriving, moving it a metre closer to the glass usually does more than anything else.

Variegation needs more light, not less

Pale sections of a leaf carry no chlorophyll and do no work, so the plant feeds itself on the green parts alone. A variegated plant needs more light than the plain form of the same species. Kept too dark it slowly reverts, putting out greener leaves to survive.

The winter here is the real adjustment

A plant grown near the equator has never known a four-hour December afternoon. The same windowsill loses a great deal between September and February, so move plants closer to the glass, expect growth to stop, water far less, and stop feeding until the light returns. None of that is a sign of trouble; it is the plant doing the sensible thing.