by Nebula Haze
Overwatering cannabis plants is the #1 mistake that beginner cannabis growers make. No more! Follow this easy cannabis seedling watering schedule for happy cannabis seedlings that quickly grow into thriving plants.
How to Water Your Cannabis Seedlings: The First 30 Days & Beyond
Below, I have a 30-day watering schedule for seedlings in 3-gallon or 5-gallon fabric pots.
- Day 1 – Give 2 cups (500ml) water per plant (at this point, your cannabis seedlings should have their leaves completely open and be in a 3-gallon or 5-gallon pot under the grow light)
- Day 3 – Give 2 cups (500ml) water per plant
- Day 6 – Give 2 cups (500ml) water per plant
- Day 8 – Give 3 cups (750ml) water per plant (every 3 days after this)
- Day 11 – Give 3 cups (750ml) water per plant
- Day 14 – Give 4 cups (1 liter) water per plant
- Day 17 – Give 4 cups (1 liter) water per plant
- Day 20 – Give 5 cups (1.25 liter) water per plant
- Day 23 – Give 6 cups (1.5 liter) water per plant
- Day 26 – Give 6 cups (1.5 liter) water per plant
- Day 29 – Give 8 cups or 1/2 gallon (2 liter) water per plant
At this point, start watering like this…
(1+ Months) Cannabis Watering Schedule
- Wait until top inch of soil is dry (for coco, wait until top is mostly dry)
- Water until you get 10-20% runoff out the bottom
- Remove runoff (test the pH if needed) and start over
Note: This is the schedule that I use, but your environment will affect how much plants drink. If plants are in hard-sided pots as opposed to fabric pots, you may need to water less often, or less at a time. The plastic sides tend to keep more water in, while the fabric pots evaporate extra water out of the sides, so plants need more water to achieve the same level of hydration.
How often should you water cannabis seedlings for the fastest growth? Follow the above watering schedule for an example timeline, and you’ll never have overwatered cannabis seedlings again!
If you notice that plants are getting droopy before you water them, give more water at a time. It’s unlikely your plants will be overwatered with this schedule, so you probably won’t need to lower the amount of water. If you would like to water less often than every 3 days, you’ll need to give more water at a time.
Typically the top of the soil will look mostly dry before watering again.
More tips on how to water plants in soil after 30 days:
- Water the plants when the top inch of the soil is dry.
- “Pick up the pot” method is the second way to check if it’s time to give more water. If the pot feels light, it’s time to water. If it feels heavy, wait a bit longer.
- Give enough water to see a little runoff water come out the bottom of the pot. Then remove the extra runoff water. Don’t let the pots sit in water of the plants are more likely to get overwatered and/or run into nutrient problems.
- Wait until the top layer of soil feels dry before watering again.
What to do if you see spots or yellowing (nutrient deficiencies) on the leaves: Check the pH of your water.
When in doubt, water less! It’s super easy to overwater cannabis plants in soil. You can always add more water but you can’t take it back out.
Here are cannabis seedlings on day 8, just after being watered.
Always give water in a circle around the base of the cannabis plant.
Important Tips
- Keep roots warm – If the floor of the grow space tends to be cold (for example in a basement or garage), keep plants from sitting directly on the ground. Warmth is important for the colony of organisms at the roots to thrive, and cannabis also tends to grow better with warm (but not hot) roots.
- Use good starting water to prevent problems. I like spring water when it’s available because it usually has a neutral pH and contains some extra minerals and nutrients that aren’t found in filtered or RO water. However, any clean source of water in the right pH range should work.
- Never let seeds dry out during germination – Moisture at all times is super important to germination. Once your seeds are exposed to water, internal processes start happening within the shell. If your seeds dry out during the germination process, it can actually kill the seeds. And once your shell has cracked open, the new baby root needs water to drink at all times.
- Don’t ignore water pH! Ideally, your water (after adding any nutrients) should be in the 6.5-7 pH range to avoid nutrient deficiencies. A little lower is okay (down to 6.3) but not higher than 7. Pure water naturally has a pH around 7, and nutrients tend to bring down the pH a little, so if you’re using good water you won’t need to think about pH. However, you WILL get nutrient deficiencies if the pH of your water is too high or low and you don’t adjust it. Luckily, to test and adjust the pH is easy with a pH kit. Learn how to adjust the pH of water.
- Give seedlings light – Think about nature, seedlings receive sunshine the moment they peak their heads above soil. You can keep you grow lights on from when you start germinating (though at 2x the normal distance, or at half power) so seedlings get light immediately. This not only keeps seeds warm but also helps new seedlings grow faster. Just be super careful not to let your soil dry out. Keep seeds moist during germination!
How to Plant Cannabis Seeds for Excellent Germination
If you haven’t sprouted your seeds yet, here is the perfect method to go along with the watering schedule above.
Basic idea: Sprout your seeds directly in the soil.
- Ensure the seed doesn’t dry out by adding 1 cup (250ml) of water first.
- Add 1 more cup (250ml) of water after 3 days if it hasn’t sprouted yet. Remember: Make sure the soil near the seed stays moist!
- Read the full germination tutorial here.
Planting cannabis seeds directly in the soil is easy and effective when done right. Nature’s method of germinating cannabis seeds works surprisingly well.
Plant your cannabis seeds and keep them warm during germination. For example, turn on your grow light (most home growers use cannabis-specific LED grow lights) and keep it 2x as far away as recommended. This will keep seeds nice and warm during germination, which greatly increases germination speed and overall germination rate. Once the seedling pops up above the soil, the extra distance from the grow light prevents the fragile cannabis seedlings from being overwhelmed by too much light.
The result? Cannabis seeds pop up as beautiful seedlings in just a few days. However, if you still don’t see a new seedling after a week, it’s time to plant a new seed and try again!
“Day 1” of the watering schedule is when your seedling looks like this.
Note: If seedlings grow tall with a lot of stem, that means they’re “reaching” up for the light. If you see this, move your LED a little closer every day until the stretching stops.
Move the grow light closer if cannabis seedlings start looking tall with a lot of extra stem.
At this point, you can follow the proven cannabis seedling watering schedule!
Which Nutrients?
Nutrients maximize cannabis yields, growth rates, and bud quality. There are many great cannabis nutrients, but one easy, cheap, and surprisingly effective nutrient system for cannabis is Dyna-Gro Grow + Bloom at 1 tsp/gallon. This combo works well to grow cannabis in any grow medium, including soil, coco, or hydro.
- Start with Dyna-Gro “Grow” at 1 tsp/gallon. This helps plants grow fast and make lots of leaves. If you’re starting in soil, you don’t need to add any nutrients for the first 2-3 weeks.
- Switch to Dyna-Gro “Bloom” at 1 tsp/gallon once buds are forming (look like little puffs of white hairs). Give with every watering until 1 week before harvest.
Use Dyna-Gro Grow + Bloom for effective, easy cannabis nutrients in soil, coco, or hydro.
Read our 10-Step Grow Guide to learn how to care for cannabis plants from germination to harvest!
