Watering Cannabis: How Often, How Much, and How Not to Kill Roots

More first grows are killed by overwatering than by anything else. Roots need oxygen as much as they need water, and a pot that never dries out suffocates them. THE CORE RULE: WET-DRY CYCLE Water thoroughly, then wait until the medium has actually dried before watering again. In soil, water when the top inch or two is dry — stick a finger in. The most reliable method is lifting the pot: learn what it weighs fully saturated versus dry, and water when it feels light. It takes two waterings to calibrate and then you'll never guess again. HOW MUCH PER WATERING Water slowly until 10–20% runs out the bottom in soil. That runoff pushes built-up salts out and tells you the whole root zone got wet. Don't water a splash every day — shallow watering trains roots to stay near the surface and leaves dry pockets lower down. In coco, more frequent smaller feedings with runoff are normal; coco shouldn't fully dry. SIGNS YOU'RE OVERWATERING - Droopy, heavy-looking leaves that curl downward like a claw. The classic tell. - Slow growth, and fungus gnats appearing (they breed in constantly wet topsoil). - The fix is not more water. Let the pot dry — it can take a week — and pick it up before you water again. SIGNS YOU'RE UNDERWATERING - Leaves droop but look light and papery, not heavy. Pot is feather-light. - Water and the plant perks back up within hours. Underwatering is forgiving; overwatering is not. SEEDLINGS ARE DIFFERENT Tiny root systems in a big pot are the classic trap — the outside stays wet while the middle dries around the roots. Water in a small circle around the stem and widen it as the plant grows, or start in a small pot and transplant up. PRACTICAL NOTES - pH your water: 6.0–7.0 for soil, 5.8–6.2 for coco/hydro. Wrong pH locks out nutrients no matter how good your feed is. - Room-temperature water. Cold shocks roots. - Fabric pots or air pots dry faster and are far more forgiving of heavy hands than plastic.