How To Fix Overwatered and Underwatered Cannabis Plants
There is a balancing act to how much water a Cannabis plant uses, and if it is absorbed by the roots, or through the foliage via transpiration. For a beginner grower, attempting to find the balance can result in either over-saturating your growing medium or under watering the plants. In this article, we explain how to diagnose the problem, the ways to restore, and our top tips.
1. Overwatering Cannabis Plants
There are many valid reasons why a Cannabis plant that is being grown indoors or outdoors, can become overwatered. The main one is down to inexperience combined with the illusion that the more water and nutrient solution is given, the faster the plants will grow.
Reasons for overwatering
• A poor-draining growing medium.
• An overzealous beginner grower.
• The pot size is too small.
• The growing medium is cold.
• Feeding when lights are off.
What Are The Signs Of Overwatering?
A Cannabis plant may not show signs immediately that it is unhappy and has become oversaturated. The leaves will begin to droop in a downwards fashion as if they have chosen not to photosynthesis as once before.
Due to the excess amount of water in the growing medium, the plants will struggle to offload the water through transpiration. This will completely disrupt the growth, nutrient uptake, and cause a grower to abandon their vapor pressure deficit chart. Depending on how thick and dense the growing medium is, can also determine how little the amount of dissolved oxygen present will be.
How To Restore
The easiest thing to do is simply to allow the growing medium to completely dry out, before considering watering again. By giving your plants 2-3 days to dry out and fill the roots with oxygen and fresh air, the roots will be encouraged to search out for new air pockets.
The dry conditions will also prevent bad bacteria thriving and limit the development of pathogens that depend on high moisture and low-oxygen environments.
What To Remember
• Allow your pots to completely dry out until they are very lightweight.
• Check on the growth structure and vigor of the plants as they begin to respond.
• Pathogens prefer low oxygen and wet conditions to live.
1. It is better to feed smaller amounts of water or nutrient solution, on a more frequent basis. Younger plants prefer this method as it encourages maximum root growth potential and allows Cannabis plants to break down the food easier.
2. Avoid feeding late at night close to lights out, and especially when plants are asleep during the darkness period. It is best to water them after the first hour when lights have turned on.
3. Using a pump and dripper lines connected to a plug timer will be your best bet at timing the watering times every day, without compromising the routine. An excellent way of reducing the physical work involved when watering.
4. The best way to judge how happy your plants are is to access them by appearance. Ideally, the fan leaves should be angled at 45 degrees facing towards the sky. When the leaves begin to droop this is a sign of over or underwatering.
5. Be vigilant of foul-smelling odors developing inside the grow room. When using organic growing mediums and liquid feeds, it is very easy for the lowest parts of the pots to become a breeding ground for unwanted bacteria.
2. Underwatering Cannabis Plants
There can be several reasons where a Cannabis plant is neglected and underwater. Sometimes it may not be practical to water your plants every day at the same time. However, once a growing medium has become totally dry, depending on how dry the air is it can lead to the plants becoming stressed, tired, and deficient of nutrients.
What Are The Signs Of Underwatering?
The plants will look lifeless and close to death, with their fan leaves facing down. The root hairs will also begin to dry out, become thin and crisp at the tips, and the way the plants transpire will be severely affected.
The leaves will become dry, crispy, and depleted, and the foliage will lose its shine and soft, waxy characteristic. The aroma of the plants will become reduced and begin to smell like dried fan leaves.
How To Restore
The key thing is not to overwater your plants but to feed them enough until you see the liquid run off at the base of your pots. It should take 30-60 seconds before there is a slow rate of water or nutrient solution forming at the bottoms.
Keep the nutrient solution the same as before and do not attempt to increase the E.C level to try and make up for the lost time.
What To Remember
• You should aim to saturate the growing medium until the signs of runoff.
• The growing medium that is being used will have an effect on how much water is retained and how much is drained away.
• Keep the temperature of your water around 15-22 degrees Celsius and avoid cold water.
1. Any foliage that has become lifeless and crisp it should be removed from the plant. Dead leaves will attract insects and unwanted guests.
2. After you have watered your growing medium correctly, wait until the containers are light enough to pick up before watering again.
3. Outdoor growers who may not always be able to water their plants on time can benefit from using a pump and drip lines.
4. Foliar feeding Cannabis plants is an excellent way to revitalize them, as well as saturating the growing medium. This will help restore the amount of moisture they can transpire.
5. Cannabis plants grown in smaller pots will always dry out quicker, so it is a good idea to plant into a larger pot that can hold much more moisture.
There is a balancing act to how much water a Cannabis plant uses, and if it is absorbed by the roots, or through the foliage via transpiration. For a beginner g
Problem: After watering, your plants start drooping. Usually the droopy leaves will feel firm and appear curled down (the whole leaf will be curled, not just the tips, which is often a sign of nitrogen toxicity). With overwatered cannabis plants, you may also notice Chlorosis (leaf yellowing that is similar to a nitrogen deficiency).
Overwatered cannabis plants are droopy with leaves that curl down. As a result of overwatering, leaves often turn yellow or show other signs of nutrient deficiencies (especially when it comes to younger plants and seedlings!)
Overwatering does not always mean you’ve been giving the plant too much water. It can also mean that you’ve been giving the plant water too often, or growing plants in a growing medium that holds onto water without enough air, or doesn’t have good drainage out the bottom.
Cannabis plants use their roots to get oxygen, almost like they’re breathing. Oxygen is dissolved in water, and there’s also air pockets in their grow medium to provide a source of oxygen. When you water your plants too often, the roots end up sitting in stagnant water. The reason your plants droop is because basically their roots are starving for oxygen.
This sick marijuana seedling has several symptoms including droopiness and leaves with brown spots that appear to be a nutrient deficiency. Surprisingly, the true cause of both problems actually is the thick, wet, muddy soil.
The main sign of a cannabis plant being overwatered are the droopy leaves, though other symptoms often appear around the same time!
Overwatered Marijuana Plants
- Drooping / Curling is the first sign of overwaterd marijuana plants
- Plants start drooping soon after watering
- Leaves are firm and curled down all the way from the stem to the leaf
- Will eventually lead to leaf yellowing and other signs of nutrient problems if not corrected
The drooping cannabis plant below did not have drainage holes (water could not drain out the bottom of the pot). After watering the plant which appeared healthy the night before, the grower came back to this drooping plant the next day – this case of overwatering was caused by too much water being held near the roots due to lack of drainage:
Solution: The best thing you can do for overwatered plants is give them time between waterings, and then start off watering slowly until things seem back to normal. Make sure that water is able to drain easily out the bottom of potted cannabis plants. Be extra careful with small plants in big containers.
How to Water Cannabis Properly
Wait until the top of the growing medium is dry about an inch deep (up to your first knuckle).
Add water until you see some at least 20% extra runoff water drain out the bottom of your pot. Go back to step 1.
If top of growing medium stays wet for a long time, you may need to give your plants less water at a time, or improve your drainage.
The goal is to be watering your plants every 2-3 days. If it needs longer to dry out, you should be giving less water at a time. If it’s drying out too quickly it should get more water at a time (or may need to move to a bigger pot).
Some growers also use the “lift the pot” method to decide when to water your plants (basically wait until your pot feels “light” since the plants have used up all the water). It’s up to you to decide what’s easier for you.
If your plant medium seems to stay wet for a long time (more than 4-5 days or so), you may need better drainage. This also can happen when growers put tiny plants in a pot that’s way too big.
This cannabis plant has green healthy leaves, but as a result of overwatering it’s stunted and small even though its more than a month old.
Make sure that water drains freely from the bottom of your container (it’s recommended that you provide enough water to get at least 20% extra runoff every time you water your plants as long as your plants are drinking well).
You should see water coming out the bottom within a minute or two after watering. Then don’t water your plants again until the soil is dry up to your first knuckle.
If your plants are already overwatered, you can try to increase the temperature and airflow to help the water evaporate more quickly. You can also use a pencil to gently poke some air holes into the growing medium to provide extra aeration and oxygen to the roots.
Whenever a seedling has droopy leaves, it means that the roots are either not getting enough water (underwatered) or not getting enough oxygen (overwatered). This seedling has been chronically watered too often, preventing the roots from getting enough oxygen. As a result, the seedling has stayed small and mostly stopped growing.
For your individual growing medium and environment, your watering method will vary, but if your plants are drooping and you’ve been feeding them a lot of water, it’s a good idea to cut back and see if that helps.
Sometimes plants will be droopy no matter what you do, and the true cause is the plant is rootbound and needs a bigger container!
If you’re growing hydroponically with your marijuana roots directly in water and you see the signs of overwatering, that means you have a problem at your roots. Either your plants have root rot which is preventing them from getting oxygen at their roots, or you are not dissolving enough oxygen into the water (you can easily increase the dissolved oxygen in your water with a quality air pump and a few air stones).
Need more help?
If your plant is experiencing “the claw” and not just normal drooping (the ends of leaves are curling like a claw or pointing down like talons), then you may actually have a nitrogen toxicity (too much nitrogen).
These Plants Are NOT Overwaterd, These Leaves Show Signs of “The Claw” which usually indicates a Nitrogen Toxicity
(“The Claw”, tips bent down, curling / clawing, dark green leaves)
Overwatering and underwatering cannabis plants are easy to do and can cause multiple symptoms including slow growth. Learn to recognize and fix these issues.