by Nebula Haze
“Don’t overwater your seedlings!” is one of the most common pieces of advice for new cannabis growers. Some growers are warned about overwatering, and go too far the other direction and don’t give enough water. But how does a beginner grower tell the difference? Overwatered seedlings look droopy, but underwatered seedlings also look droopy.
Do my droopy seedlings need more or less water? Find out below!
Today, learn how to tell the difference between overwatered and underwatered cannabis seedlings.
Step 1: Compare with a proven seedling watering schedule
Cannabis seedlings don’t drink a lot of water, but “a lot” can mean different things to different growers. Sometimes it helps to get actual measurements, so you can compare.
Seedlings just need a little water at a time.
Water in a small circle around the base of seedlings. Don’t soak the pot.
This is an example watering schedule for a seedling in a 5-gallon fabric pot for first 30 days.
- Day 1 – Give 1 cup (250ml) water per plant
- Day 3 – Give 2 cups (500ml) water per plant (wait 3 days after this one since you just upped it)
- 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 (more or less often as needed)
Your seedling may need more or less water depending on the pot size, temperature, humidity, and how strong the grow light, but this gives you an idea of how much water a cannabis seedling needs on average.
If you look at the above schedule and you are giving just 1 cup (250 mL) of water in a week, you’re definitely underwatering your seedlings. But if you’re giving your 1 week old seedling 4 cups (1 liter) of water at a time, it’s too much.
This is plenty of water for a small seedling.
Still not sure? The appearance of leaves, pot weight, and type of soil also gives clues as to whether you’re looking at overwatered vs underwatered cannabis seedlings.
Step 2: Compare with pictures: overwatered vs underwatered cannabis seedlings
Look at these pictures if you’re still not sure whether your droopy seedling is getting too much or too little water.
Too Much Water
There are a few ways to “over water” your seedlings. Sometimes called “damping off” or giving seedlings “wet feet”, this results in slower growing seedlings that may show deficiencies.
- Too much water at a time
- Watering too often
- No drainage holes to let out excess water
- Grow medium too thick and stays wet a long time (“muddy”)
If the grow medium looks soaking wet, it’s way too much water for a seedling. If the pot feels heavy, that’s another sign it’s full of too much water.
Overwatering picture 1: Classic overwatered cannabis seedling. The grow medium looks wet all over, the leaves droop downwards.
Overwatering picture 2: This cannabis soaked grow medium and droopiness show this seedling is overwatered.
Overwatering picture 3: Overwatered seedlings often show yellow leaves or nutrient deficiencies, especially if the overwatering goes on for a while and the soil never gets a chance to dry out.
Overwatering picture 4: Most cannabis seedling “nutrient deficiencies” are actually caused by overwatering. Notice in the next picture how the soil is soaked throughout the pot. Combined with the brown spots, brown curling tips, and overall yellow color, this seedling displays a clear case of overwatering.
Overwatering picture 5: If the grow medium is so wet that it’s growing green algae on top, you are definitely overwatering.
Overwatering picture 6: When left unchecked, overwatering can cause all kinds of unusual symptoms, like the curling leaves, brown spots, and overall sad appearance of this seedling. But the green algae on the soil of this seedling gives a clear sign the seedling is getting way more water than it can drink.
Too Little Water
It’s less common to “under water” your seedlings, but it happens, especially for beginner growers who are warned over and over not to overwater their seedlings. Underwatering is mainly caused by…
- Not enough water at a time
- Watering too infrequently
- Poor quality soil that doesn’t hold much water
If the grow medium looks bone dry even around the base of the soil, it’s usually not enough. If you pick up the pot, the seedling may feel unusually light, as there is no water inside to give it weight.
Underwatering picture 1: Classic underwatered cannabis seedling. The grow medium looks completely dry, and the seedling looks droopy. Underwatered seedlings leaves tend to look more thin and limp than overwatered seedling leaves. Chronically underwatered seedlings often appear either pale green like this (or dark green as you’ll see below).
Underwatering picture 2: This seedling has barely grown at all due to lack of water. The leaves are dark and curling. The overly dry grow medium looks pale and dusty from lack of moisture. If you tried to pick up this cup, it would feel as light as a feather.
Underwatering picture 3: A severely underwatered cannabis seedling seems to just wilt as if there’s nothing holding it up. This seedling was growing fine at first but the grower forgot to water it. Seedlings with no water inside often have leaves that appear limp and lifeless. Note: Very high temperatures can cause similar symptoms.
Underwatering picture 4: This cannabis seedling has been thirsting for more water since it germinated. Chronically underwatered seedlings often appear either pale green or dark green. This underwatered seedling is so dark green it looks like it has a nitrogen toxicity, but the real problem is it needs more water.
You should be getting a better idea of what overwatered seedlings look like compared to underwatered seedlings.
But the best way to prevent having to identify which is which is simply to start with good cannabis soil and follow a proven day-by-day seedling watering schedule.
Let’s end this article with a happy seedling that is loving life!
This marijuana seedling is getting the perfect amount of water.
About the Author Nebula Haze
Nebula Haze is GrowWeedEasy.com’s co-founder and main author. Established in 2010 to make it easier for home growers to produce great quality weed. GrowWeedEasy.com is the most comprehensive online free educational resource for growing cannabis at home.
Located in San Diego, California alongside co-founder Sirius Fourside, Nebula has written hundreds of cannabis cultivation tutorials, grow journals, and guides covering every aspect of indoor home cultivation. Her side-by-side grow experiments and growing tutorials have been featured in publications like Skunk Magazine and Cannabis Business Times.
