How To Fix Over or Underwatering Your Cannabis Plant

Too Long, Didn't Read:

• Balance: Don't over or underwater. Find the middle ground.

• Signs: Droopy leaves/heavy pot = overwatering. Brittle leaves/light pot = underwatering.

• Recovery: Let soil dry for overwatering. Water slowly for underwatering.

• Schedule: Consistent timing is key, ideally after lights on. Check soil dryness.

• Amount: Use the 10% rule as a guide, adjust as needed.

• Observe: Your plants will tell you what they need. Pay attention!

Water is the driving force for all living things, and when it comes to cannabis plants, finding the right balance is key.  Watering cannabis plants is an essential part of your journey as a grower, and how your plants can use nutrients, allowing for optimal health and vitality.

In this article, I will guide you through all the important factors you need to know. This will cover such pointers as when and how much you should water, allowing you to easily develop an awareness of underwatering cannabis plants and overwatered cannabis plants. Combined with the best cannabis watering schedule that is most practical for you. 

You will be extremely surprised at how straightforward watering cannabis plants can be, so get ready to hold the keys to success and become a master of watering your plants from seed to harvest!

Why the Right Amount of Water Matters 

Balance is not something you find; it's something you create! Why does the right amount of water matter? Well, let’s break it down with a simple analogy to make you think outside the box and fully grasp the art of watering cannabis. 

Think of it like this: your plant needs food (nutrients) to thrive. If the roots are constantly soaked (overwatering), they can't breathe properly and can't absorb those nutrients.  It's like trying to eat with your mouth full – you just can't do it. On the other hand, if the soil is bone dry all the time (underwatering), the plant can't take up the nutrients because it needs water to dissolve and be transported. It's like trying to eat a dry cracker with no drink – tough going.

Cannabis plants will react the exact same way when it comes to under or overwatering. Too little and your plants won’t have enough water to keep the roots happy, and the leaves can become dry and brittle. Too much water and your plants will begin to droop and take a few days before they bounce back. 

How do I Know I’ve Watered My Plant Wrong? 

Well, the truth is you won’t know immediately, and it can take several hours or even a full day before you learn your lesson the hard way. 

If you find that the pots are frequently very dry and they feel lighter more often than not, then this is an indication you may need to give them more water and do a better job at saturating the growing medium and roots.

On the other hand, in the event your pots are heavy to lift up, and the growing medium is visibly wet or soggy, lay off the water. The waiting time may vary between several hours or even a full day before you can comfortably water them again.

Inserting your finger down the side of the pots is the quickest way to determine how wet or dry the growing medium has become. Using the back of your hand and lightly pressing on the surface is also a great way to see if the center of the pots is too wet or if you are ready to apply another round of water.

In order to become a great grower, you will need to become familiar with the visual signs that show how healthy and happy the plants are. Here is a checklist you can use to see if you have watered your plants wrong:

• Do the leaves feel paper-thin, becoming dry and brittle to the touch? 

This means you’ve underwatered your cannabis plant! 

• Are your plant’s leaves drooping and have lost their original vigor? 

This means you’ve overwatered your cannabis plant!

• Has the growing medium become dry and very light when lifting?

This means you’ve underwatered your cannabis plant!

• Are the leaves turning lighter green color and have become pale in color?

This means you’ve overwatered your cannabis plant!

• Have your plants seemed to have slowed down growing? 

Clear sign you have a watering problem in general, which means you’re either underwatering or overwatering your cannabis plant!

• Can you see brown spots and rusty colors at the edge of the foliage?

This means you’ve overwatered your cannabis plant!

• Are the edges of the fan leaves begun to curl downwards?

This means you’ve overwatered your cannabis plant!

• Have the roots become yellow and thinner

This means you’ve underwatered your cannabis plant!

Signs I’ve Overwatered My Plant 

They say that mistakes are costly and somebody must pay, and that expression certainly rings true with a room full of overwatered weed plants. It is not the end of the world and only a slight setback on your journey to becoming the best grower you can be.

Overwatering a cannabis plant will cause the plant’s leaves to change shape and begin to droop downwards. It can take a full day in some cases before the plants bounce back to full vitality.

If the growing medium has become soggy and heavy, then you’ve overwatered your cannabis plant. You will instantly know, based on the weight of the pots, combined with drooping leaves. You may also notice the color of the leaves has transitioned to a light pal green with veins showing on the leaf surface, another clear sign the cannabis plant is overwatered.

You only need to lift the pots off the floor a few inches to feel how much water they contain. If it becomes a struggle, then this is another sign you have an overwatered cannabis plant and should wait until they are light enough to comfortably pick up.

After watering, if the saucers underneath your pots are close to full or, in a worst-case scenario, overflowing, you can bet your @ss you are overdoing it, big time! 

How Can I Help My Plant to Recover From Overwatering? 

So, what can you do to save an overwatered cannabis plant? 

• Be patient and let the moisture levels return to normal over a 24-48 hour time frame.

• By using half the volume as before for the first few days.

• You can spray the leaves and foliage with water to give the growing medium and roots time to fully recover when your plants are in the vegetative growing phase (18/6).

• Place a dry towel underneath the pots and let the excess water soak up before removing.

• You can re-pot the feminized cannabis plants with a perlite-rich mixture to promote faster drying times.

• Add a layer of hydroton at the base of the pots, enhancing drainage and aeration.

Signs I’ve Underwatered My Plant 

• Your plants begin to lose vigor and start to wilt with drooping leaves.

• The growing medium will become dry and the pots will be very light when lifting.

• Your plants will become stunted, and growth will significantly cease.

• Foilage will become dry, and thin and have a lifeless appearance.

• The stems, leaves, and branches will become weak and brittle.

• Plant vitality will be significantly affected.

• The tips of fan leaves will begin to curl downwards and claw.

How Can I Help My Plant to Recover From Underwatering? 

• Add small amounts of water until the structure returns to normal.

• Place a saucer underneath the pot, fill the saucer, and allow the growing medium to wick water.

• Gently water around the edge of the pots, allowing slow absorption.

• Spray the plant leaves with some water, making sure you saturate the tops and undersides.

• Increase the relative humidity levels in the grow room during 18/6 only.

When and How Much Should I Water My Cannabis Plants? 

Knowing when and how much you should water your plants will be based on the light intensity, the growing medium you are using, the size of the pots, and the environmental settings.

One of the best habits I have developed over the years, and I noticed my plants loved this style of watering, was to water at the same time every day. Consistency is key when growing top-shelf cannabis buds, and finding the right window of opportunity should fit your work schedule and social calendar.

Another excellent way to make sure your cannabis plants continue to thrive when creating a watering schedule is to apply water when your grow lights have turned on, and I find one hour after turning on is the best time frame. 

Avoid watering your plants when the lights are off. If you are not able to water within an hour of the lights turning on, find the most practical time for your (social) schedule and stick to the same time.

If you are not fully sure when to water your plants, one of the best pieces of advice I can offer is to check the dryness factor. This means how dry the growing medium has become. Growing mediums with a high ratio of perlite inside will tend to dry out faster.

A method to check the dryness factor, which has worked a charm for me, is to insert your finger a couple of inches down the side of the pot. If your finger is still dry and shows no signs of moisture, the medium is too dry and needs saturating. 

Once you get the hang of the dryness factor, you will know if the growing medium is too wet and soggy. Base this on the weight of your pots, the finger test and if in doubt, just wait it out.

One of my golden rules that will allow you to be efficient and consistent when knowing just how much water to give your plants is to use the 10% rule. This simply means to divide the volume of the pot size by 10 and use that exact volume of water as shown below.

• 1 gallon sized pot = 12,5 ounces of water

• 2 gallon sized pot = 25,3 ounces of water

• 3 gallon sized pot = 37,2 ounces of water

• 5 gallon sized pot = 64,2 ounces of water

• 7 gallon sized pot = 89,2 ounces of water

I would recommend that you only water your cannabis seedlings once over a 24-48 hour period. If you can do this when the lights are on, and try your best to do so at the same time each day, or every two days, depending on the size and development of your cannabis plants,  then you are on the road to success in becoming a plant watering expert!

How Much Water Should You Give Your Seedlings And When? 

One of my favorite methods of making sure my seedlings are properly watered is to use a plastic syringe. For the seedling stage, using a 20 ml syringe allows me to apply pressure slowly to produce a slow output and avoid overwatering.

Now, this does not mean that your plants only need 20 ml of water and may need much more. However, the syringe is a great and easy way to avoid unintentionally drowning them and ending up with an overwatered baby cannabis plant. 

Watering too close to the stem keeps roots from spreading. Instead, water a bit further out to encourage roots to grow outward, creating a stronger, deeper root system.

Measuring cups work well. The type of plastic measuring beaker I am referring to is the same one you may use for cooking and allows you to work with a milliliter or ounce scale. 

Another option and easy-to-follow method is to take a small bottle of water (250 ml / 8 ounces)  and pierce a hole in the top with a pair of scissors. Gently squeeze the bottle and water around the edges of the pot and avoid squeezing too hard. Take your time and go slowly.

How Much And When Should You Water Your Cannabis Plants in The Vegetative Stage? 

As your cannabis plants grow under 18 hours of light and 6 hours of darkness. Remember, cannabis plants love consistency, so it is time to get the measuring beaker out again. Just follow the 10% rule and keep the watering schedule as simple as possible.

During the vegetative stage, my favorite way to make sure my cannabis plants do not become overwatered or the roots become waterlogged in a short time frame is to slowly water around the edges of my pot. The growing medium will absorb and wick the water back to the center, ensuring there is plenty of oxygen and moisture available.

If the pots feel heavy, and if your finger feels wet after inserting down the sides, then simply wait again before watering, and base this judgment on the dryness factor.

Now, it is important to know that as your plants develop during the vegetative stage, the time between watering may vary from 24 hours to 48 hours. The reason is that as the roots grow and expand in size, they will be capable of using more water for the plant’s growth and progression. 

Just think, the bigger the plants get, the more water they will use to support new growth, so be extra vigilant during the growth period. 

When And How Much Should You Water Your Flowering Cannabis Plants?

Once you switch your timers over to 12 hours of light and 12 hours of dark, your plants will now enter the flowering stage. 

Water at the same time each day during 12/12, just as recommended during the vegetative stage, as the same principle applies when your plants are in flowering mode. Pick a time that is most practical to you and stick to it every time you water, creating the ultimate consistent watering schedule.

You may be using more grow lights than when your plants were in the vegetative stage, and if you are like me, then you will be cranking out full power and light intensity or may have decided to add a second or even third grow light depending on the size of your growing space.

In this case, then your plants will drink more than before, and the right amount to give them should be based on the dryness factor, what the leaves look like, and the rate those leaves transpire water, causing the growing medium to dry out faster than before. 

Flowering cannabis plants should be grown in an environment with a lower relative humidity level closer to the 45% - 50% mark. As a result, your plants will use more water and nutrients than at any other time, so pay close attention to how wet or dry the growing medium has become every 24 hours before considering water again.

Using the 10% rule should still be the recommended guideline, however, always pay close attention to what your cannabis plant is telling you through how she’s behaving. Take the time to lift your pots and test how dry or saturated the growing medium has become. 

To Wrap Up

Mastering cannabis watering takes practice and observation. Don't be discouraged by occasional hiccups – every grower has been there.  By understanding the signs of over and underwatering and by paying close attention to your plants' needs, you'll develop a feel for the right balance.  Remember, consistency is key, and every grow is a learning experience. 

Happy growing!