What it is
Moving the lamp away from the plant tops. Light drops very fast with distance: if you double the distance, roughly a quarter of the light reaches the leaf (with small lamps; big panels lose less).
When it is done
When the tips turn white or yellow (light burn), when it is very hot up top, or during the pre-flower stretch, when the plant gets closer to the light by itself.
How far away
It depends on the lamp: each manufacturer gives its distance (for LED it is usually 30 to 60 cm in flowering). The most accurate way is to measure with a par meter and aim for 600 to 900 at the tips. A home test: if you put your hand at tip height and after 30 seconds the heat bothers you, it is too close.
The balance
Moving it too far away is also bad: less light reaches the plant, it stretches and yields less. The right distance is the closest one that doesn't burn.
▲ Pros
- No burn
▼ Cons
- Up to 5 % fewer harvest grams, depending on the hours with the lamp up
🎮 Practice it in UnderGrow
You raise it by tapping light (in climate) › raise the lamp, and it applies only to that spot: each indoor spot has its own. It no longer burns, but less light reaches the plant: in flowering, up to 5 % less harvest, in proportion to the flowering hours with the lamp up (if you raise it only at the end, it barely costs anything). You can lower it again.
▶ Play free