Cannabis Seedling Care: The First 3 Weeks Done Right

Light: 18/6, dimmed, and hung high

Run 18 hours on and 6 off. Dim your LED to 25-40% and hang it 24-30 inches above the canopy. A seedling under full-power light will bleach, stall, or grow tight and yellow.

Humidity and temperature

Target 65-70% relative humidity and 72-78°F. Seedlings drink through their leaves as much as their roots at this size. A humidity dome for the first week helps, but vent it daily so the surface is not permanently soaked.

Watering: a shot glass, in a ring

Water in a small circle a couple inches out from the stem, not directly on it. That encourages roots to reach outward. A shot glass worth every day or two is plenty in a small pot.

Overwatering is the number one seedling killer. Drooping with wet, heavy soil means too much water, not too little.

Nutrients: wait

In living or lightly amended soil, the seed and the medium carry the plant for 2-3 weeks. Start at quarter strength only when the third or fourth set of serrated leaves appears and the plant is clearly hungry.