A cannabis seedling in its first 2 weeks needs roughly 15 to 60 ml (1 to 4 tablespoons) of water every 2 to 3 days, poured in a small ring around the stem instead of over the stem itself. Water only when the top 1/2 to 1 inch of the medium feels dry, and never let the pot sit in standing runoff. Overwatering kills more seedlings than underwatering, because constantly saturated soil starves roots of oxygen and invites damping-off.
Cannabis Watering Schedule for Outdoor Pots: How Often to Water
Week-by-week cannabis seedling watering schedule
The amounts below assume one seedling in a 4 to 6 inch pot under a humidity dome or in a warm, still grow space. Adjust for pot size, airflow, and light intensity.
overwatering vs underwatering cannabis
Days 1 to 3
- Water 10 to 15 ml once, on the day you plant the sprouted seed.
- Leave the dome on and do not water again until the surface starts to dry.
- No nutrients. The cotyledons supply everything the sprout needs.
Days 4 to 7
- Water 15 to 30 ml every 2 to 3 days.
- Pour in a 1 to 2 inch ring around the stem to pull roots outward.
- Crack the dome for a few hours a day once the first true leaves open.
Days 8 to 14
- Increase to 30 to 60 ml per watering as the root ball fills the pot.
- Shift to a wet-to-dry cycle: water when the top inch is dry, not on a clock.
- Remove the dome once two or three leaf sets are open.
How often should you water a cannabis seedling?
Every 2 to 3 days is typical in week 1, tightening to every 1 to 2 days by the end of week 2 as the plant grows. A cool or humid room stretches that to 3 to 4 days, while a warm, breezy tent shortens it. The roots, not the calendar, set the pace.
How do you tell when a seedling needs water?
Lift the pot. A dry seedling pot feels feather-light, while a freshly watered one has clear heft. You can also poke a finger or moisture meter 1 inch into the medium; if it feels damp, wait a day. Drooping leaves that perk up after watering are thirsty, while drooping leaves on wet soil signal the opposite.
Cannabis Watering Schedule: Soil vs Coco
Should you water directly on the stem?
No. Pouring on the stem keeps the crown wet, which encourages damping-off and stem rot in young plants. Water in a ring 1 to 2 inches out from the stem so roots grow toward the moisture. Once the plant is well rooted, you can water the whole pot evenly.
What water pH and temperature do seedlings want?
Aim for pH 6.0 to 6.5 in soil and 5.5 to 6.0 in coco or hydroponics. Use room-temperature water around 65 to 75 F, since cold water shocks tender roots. Let tap water sit out overnight if chlorine levels are high.
Humidity, temperature, and light for weeks 1 and 2
- Humidity: 65 to 70 percent with the dome on, tapering to 55 to 60 percent by day 14.
- Temperature: 70 to 80 F during lights-on hours.
- Light: low intensity, 18/6 or 20/4, kept 18 to 24 inches from an LED or fluorescent.
- Nutrients: none in amended soil; start at one-quarter strength in coco after day 10.
Overwatering vs underwatering in seedlings
Overwatered seedlings look droopy, pale, and stalled, with heavy pots and sometimes algae or fungus gnats on the surface. Underwatered seedlings wilt, curl upward at the leaf edges, and feel light as paper. When in doubt, wait a day: a dry seedling recovers fast, a drowned one rarely does.
Does pot size change the 2 week schedule?
Yes, and it is the biggest variable. A solo cup or starter plug dries in 1 to 2 days and needs small, frequent sips. A seedling planted straight into a 3 to 5 gallon pot dries slowly, so 30 to 60 ml every 3 to 4 days is often enough, watered in a widening ring. Never soak a large pot for a tiny seedling; unused moisture sits and sours.
FAQ
Can you overwater a seedling with just a few drops?
Rarely, but daily mini-pours keep the top layer constantly wet and raise damping-off risk. Let the surface dry between waterings.
Should seedlings get runoff?
No runoff is needed in the first 2 weeks. Water just enough to moisten the root zone, then stop.
What if a missed watering made the seedling wilt?
Water lightly and move the pot out of direct light for a few hours. Most healthy seedlings bounce back within a day.