Lesson 1. Window directions and how much light your home really gets

Remember one idea and half your plant problems will disappear: for a plant, light isn't “coziness” or “a nice view from the window” — it's literally food. Light drives photosynthesis: the leaf turns light, water and carbon dioxide into sugars, which the plant uses to build itself and get energy. No light, no food. This leads to an unexpected but very important conclusion: the less light, the LESS you need to water. In shade a plant works slowly and uses little water, so extra water in the pot just sits there and kills the roots. That's why light and watering can't be considered separately — they form one “light — water — roots” system, and the whole course is built around it. People consistently overestimate how much light they have at home. The eye adjusts to darkness very well, and a room that seems “bright” to us may be twilight for a plant. So next we'll learn to judge light not by eye but by simple, checkable signs.

The direction a window faces sets the “ceiling” for how much light the room gets. You can't change it — but you can choose a plant to match it. — South-facing window. The brightest and warmest: direct sun for most of the day. Paradise for cacti and succulents. But in summer many plants on a south windowsill get sunburned, so at midday they are often shaded with a sheer curtain. — East-facing window. Gentle morning sun, then even, indirect light. One of the most convenient options: bright, but it doesn't scorch. Suits almost any plant. — West-facing window. Similar to an east-facing one, but the sun comes in the afternoon and it's hotter. Also a good, bright option. — North-facing window. Almost no direct sun; the light is even and weak. That's not “bad” — it's just not much light. This is the place for shade-tolerant plants (snake plant, ZZ plant, cast-iron plant), while flowering and variegated plants go hungry here. An important caveat: all of this is for the Northern Hemisphere. In the Southern Hemisphere the sunniest window faces north and the shadiest faces south.

Even at the sunniest window, light fades very quickly as soon as you move farther into the room. A rough but practical rule: 1–2 meters from the window, a plant gets several times less light than right on the windowsill, and deep in the room (3–4 meters) there's very little light left — that's already “shade,” whatever your eye tells you. A simple way to check the light without a light meter is the hand-shadow test. At the brightest time of day, hold your hand over a sheet of paper where the plant stands: — A crisp shadow with sharp edges — bright light (often direct sun). — A fuzzy but visible shadow — moderate, indirect light (partial shade). — A barely visible shadow — low light (shade). One more thing: heavy curtains, sheers, dirty glass, a balcony above the window and trees in front of it noticeably cut the light. Clean glass and light-colored walls, on the other hand, add to it.