In soil, overzealousness does more harm than drought. Cannabis loves the cycle “wet → moist → almost dry,” and only then the next shot of water. For most indoor setups, a healthy rhythm is every 2–3 days, but not by the calendar—based on the plant’s own signals and the pot’s weight. This guide shows how to read leaves, how to use weight like a pro, and how to water seedlings day by day so they grow fast rather than swim.
Plant signals: what “thirst” and “overwatering” look like
Light water hunger (a good time to water)
- Leaves stop “praying” to the lamp and sit a bit more horizontal; stems still firm.
- The top 1–2 cm of soil is dry; the pot is clearly lighter.
Too little water for too long
- Leaves limp like a “rag,” can curl downward; soil pulls away from the pot walls.
- After watering they come back to life within 1–3 hours—a sign you only overdid the waiting.
Overwatering (too often / without drying)
- Leaves also droop, but stems remain firm; soil is cool, heavy, sometimes “jelly-like.”
- New growth slows; yellowish spots appear despite a “full belly.”
- Fix: let it dry properly and improve drainage.
Iron rule: water when the plant and the pot say “yes,” not because 48 hours have passed.
The pot weight method — the simplest “when” gauge
Want certainty? Weigh the pot after a good watering and again right before the next watering. The difference is your compass.
- After the first thorough watering (technique below), wait 15–30 min, pour off excess from the tray, and weigh: that’s your wet weight.
- Before the next watering, weigh again: that’s your dry weight.
- Watering start threshold: when the pot has lost 35–45% of the wet–dry difference, or the top 1–2 cm are clearly dry — water.
No scale? Consistent “lifting” by hand is enough. A kitchen scale up to 10 kg (or a bathroom scale) is cheap and teaches precision.
How much water to pour (5/10/20 L pots)
In soil we don’t do big “runoffs” like in coco. Water slowly and in portions until the whole root ball has a drink and a light runoff appears.
- 5 L pot: usually 0.7–1.0 L for a full watering
- 10 L pot:1.2–1.8 L
- 20 L pot:2.0–3.0 L
Technique: pour in 2–3 passes around the perimeter and center, with 1–2 minute pauses so water can soak in. If the surface repels water (hydrophobic crust), lightly loosen it with a stick and water even more slowly.
pH for growing cannabis in soil: keep 6.3–6.8 (full nutrient availability zone).
Water temperature:18–22 °C — ice-cold water slows uptake.
Seedlings & young plants — day by day (first 14 days)
The most common mistake is “drowning” seedlings in huge pots. A small root cannot “handle” 10 liters of mud. Either start in smaller containers (0.3–0.5 L), or in a large pot water only a small ring around the seedling.
- Day 0 (sowing / planting a sprout): medium pre-moistened, not muddy. Mister instead of watering can.
- Day 1–2: water 20–40 ml around the stem (ring 6–8 cm diameter). The rest of the pot stays just moist.
- Day 3: break. Watch whether the ring has dried on the surface.
- Day 4–5: again 20–50 ml into the ring. If the seedling has its first true leaves, enlarge the ring to 10–12 cm.
- Day 6–7: break. The pot starts to get lighter.
- Day 8–10: water 50–120 ml. You can add a second ring (water two rings: the old and the new) to encourage roots to “wander.”
- Day 11–14: if it’s a 0.5 L pot—it’s usually time for the first more complete watering (until a few drops appear in the saucer). In a larger pot, stick to the ring method until the plant has 5–6 nodes.
After 2–3 weeks, seedlings become small bushes. From here you usually shift to a rhythm of every 2–3 days (sometimes more often with high temperature and low humidity).
Pots & soil choices that matter
- Fabric pots breathe and air-prune roots → more even moisture, fewer stagnant pockets.
- Plastic pots hold water longer → handy in heat, but easier to overwater.
- Cannabis soil mix with 15–30% perlite (or similar) boosts airflow and evens the wet–dry cycle.
- Drainage: always holes plus a tray with an outlet. Don’t leave plants “in a puddle.”
- Airflow at soil level: a gentle breeze helps evaporate excess — you water less often, but healthier.
Feeding in soil: water → water → water with nutrients
Living, “hot” soils (super soil) can feed themselves, but a typical cannabis mix likes the pattern: water → water → water with nutrients. With a 2–3 day watering rhythm, this lands about every 6–9 days. Start at half label dose; leaf tips are your barometer — a lightly “toasted” tip = enough.
Example week in a 10 L pot (vegetative stage)
- Monday: full watering 1.4 L (pH 6.5).
- Tuesday: rest; leaves “pray”; pot still heavy.
- Wednesday: soil dry on 1–2 cm; pot much lighter — do nothing (still holding).
- Thursday: time to water — 1.2 L plain water (no nutrients), slowly, in passes.
- Friday: rest.
- Saturday: check weight — if light, water 1.3 L with half the veg nutrient dose.
- Sunday: rest; leaves firm; color deep.
This is only a sketch. Your conditions (temperature, humidity, LED power, plant size) will shift the days — listen to the pot and the leaves.
Common watering mistakes with cannabis in soil
- “A little every day to be safe.” Straight path to a forever-wet root ball and weak roots. Water less often but to full (with a light runoff), then let the soil breathe.
- Ice-cold tap water.10–12 °C blocks uptake and suffocates roots. Let water warm to 18–22 °C.
- No pH control. In soil keep 6.3–6.8 — outside this range “weird” deficiencies appear despite nutrients.
- Rigid calendar. In heat the plant drinks like a dragon, in cold like a cat. The 2–3 day rhythm is a compass, not a dogma.
- Soil pulling from pot walls. You’re drying it to a brick. Before the next full watering, break the crust on top and pour slower, in rounds.
Simple pre-watering check (every time)
- Finger test to knuckle depth: dry?
- Lift the pot: light like a shoebox?
- Leaf posture: horizontal or slightly drooping, without limpness?
If 2 out of 3 say “yes” — water. If only the surface is dry and the pot is heavy — not yet.
Watering sets the tempo, not punishment or reward
Growing marijuana in soil is rhythm. You don’t feed “just in case,” and you don’t keep it “starving” on purpose. Learn the wet–dry dance where the pot sets the beat and the leaves are your metronome. Once you slip into that groove, “every 2–3 days” stops being a guess and becomes a habit. The plant pays you back with thicker stems, faster growth, and a stress-free color you can’t mistake.
