by Nebula Haze
Overwatering cannabis seedlings is the #1 mistake that beginner cannabis growers make. No more! Follow this easy cannabis seedling watering schedule and you’ll have happy, thriving cannabis seedlings.
How to Plant Cannabis Seeds for Excellent Germination
Sprout your seeds directly in the soil. Ensure the seeds don’t dry out by adding 1 cup of water every 3 days before they sprout. 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 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, after a week, it’s time to plant a new seed and try again!
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.
How to Water Your Cannabis Seedlings: The First 30 Days
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
- Continue giving 1/2 gallon (2 liters) per plant every 3 days. You may need to give more at a time or more often as plants get bigger. If plants get droopy before being watered, you should give more water at a time, or water more often.
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’ll need to water far less often. The plastic sides tend to keep more water in, while the fabric pots evaporate extra water out of the sides, so plants need to drink more often.
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 run into nutrient problems.
- Wait until the top layer of soil feels dry before watering again
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.
- 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.
Read our 10-Step Grow Guide to learn how to care for cannabis plants from germination to harvest!
