Everything you need to know about growing cannabis at home

How to Prevent Overwatering and Underwatering Your Cannabis Plants

by | Mar 14, 2022 | Getting Started, Troubleshooting

It’s not surprising that watering is one of the most common mistakes new cannabis growers make. After all, it can be tricky to know how much water your plants need and when they need it. This article explains what watering too little or watering too much will do to your cannabis plants, as well as some helpful tips for fixing these problems.

Why are overwatering and underwatering so common for new cannabis growers?

Watering is one of the first mistakes that new growers encounter when growing cannabis. This is because watering correctly requires paying attention to watering your plants accurately and in a timely manner. Plants need water to grow and produce the buds we love to smoke, so watering your plants is very important. When a plant receives the water it absorbs it and it is then transported throughout the plant, where this process of transpiration cools down the leaves. This allows for photosynthesis to occur which provides energy for your plants to grow. Overwatering or underwatering can lead to many problems such as overwatering leading to root rot, which is when fungi start eating away at the roots, while underwatering leads to a nutrient deficiency. Let’s take a closer look at these problems and how to solve them.

What happens when I overwater my cannabis plant?

When watering your cannabis plants avoid watering too much and always check the soil before watering to make sure it is dry. Overwatering will cause root rot, which happens when fungi start eating away at the roots. As a result, leaves may begin turning yellow or brown between leaf veins while wilting occurs on older leaves first. If these symptoms appear, reduce watering immediately to halt the progression of an already established root rot. If your plant is suffering from root rot you will need to flush out all excess water and rehydrate your roots with healthy nutrient-rich water so that they can heal. You should also remove dead or dying leaves as this allows for airflow which reduces humidity near the soil.

How do I fix overwatering my plant?

The simple answer to this is to stop watering the plant so much. The pot should also have holes in the bottom to allow excess water to flow through to help prevent root rot. If watering your plants is too much for you, it could be beneficial to invest in self-watering containers. These are great ways of watering because they release the perfect amount of water every time, which prevents overwatering. Since these systems deliver water evenly and regularly without human interaction, there’s no risk of over or underwatering your cannabis plants.

What happens when I underwater my cannabis plant?

Before watering your cannabis you should always check the soil before watering it to make sure that it is dry. If all of the water has not been absorbed by your plant roots, then do not water until they are dry again. An underwatered cannabis plant can lead to a nutrient deficiency. Nutrient deficiencies occur because the roots cannot absorb nutrients from the soil and there is a lack of nutrient uptake, so they are absorbed by leaves instead and transported throughout your plants in order to grow and produce buds. This results in less energy for your plants which causes them to stop growing or slow down which leads to stunted growth. If your plants are not receiving adequate watering they may also begin to wilt and the older leaves will be affected first while younger ones remain green, but eventually, the yellow leaves will develop brown spots, turn brown, and fall away from lack of nutrients which leads to wilting. Over time if a plant does not receive enough water it will eventually die.

How do I fix underwatering my plant?

First, you should increase your watering frequency. Flushing out the extra water helps prevent nutrient deficiencies, which is when your plants are not receiving adequate watering they may begin to wilt and wilting occurs from lack of nutrients. You should also make sure that you have a drainage system whether it be drainage holes in your pots or self-watering containers in order for any excess water to flow through and prevent overwatering. If watering your plants is too much for you, it could be beneficial to invest in self-watering containers as noted above.

How will I know it is the right time to water my cannabis plant?

There are a few ways to tell when you should water your plant.

The first is by checking the color of the topsoil, if it’s lighter than usual watering might be necessary. Checking the soil for dry conditions regularly will help prevent overwatering and underwatering because watering too much can cause root rot. To do this, simply stick a finger in the topsoil and if it is bone dry all the way down to your first knuckle, then it is ready to water. It can also help to know the weight of the plants in your pot, meaning if you pick up the pot and it feels light then it is time to water. Always monitor the weight of the pots to get a feel for when there is enough water in them and when there is not.

Another way of watering your plants is by checking them for droopy leaves. If they are not as perky as usual, chances are that you should water them immediately because over or underwatering can cause nutrient deficiencies which result in a lack of nutrients being absorbed into the root system resulting in wilting.

The last way is by watering your plants as you normally would and watching for signs of recovery or lack thereof. If it drinks up all the water immediately then good, but if not then they need watering because drying out can also result in nutrient deficiencies which results in a lack of nutrients being absorbed into the root system resulting in wilting.

Why should I PH my water?

You will want to make sure that you PH your water before watering your plants. When watering, it is important to take into consideration what kind of medium you are watering with because some grow mediums require more or less caution than others; however, we will go over them in more depth below and in another article. If your PH is too high or too low this may result in deficiencies or lack of absorption. Make sure to also PH your runoff water, or water that is drained from your plants. This will give you a more accurate gauge of the PH of the water when it gets to your roots as the growing medium will affect your PH levels.

What is PPM?

PPM stands for parts per million, which means the level of nutrients left behind after watering your plants or mediums with water. Lower proportions are better because they allow you to control how much fertilizer you give your plants at one time instead of watering them too often and wasting fertilizer.

What is the correct PH for different growing mediums?

If you are watering in soil, your PH levels should be between six and seven; however if watering with coco coir or hydro, it should sit at a range of 5.5 to 6.3 pH levels. You can use a tool called PPM, which we explained above, to monitor the water too and ensure your plants are receiving the right amount of nutrients.


All plants need water to survive, that’s why it is important to get the right amount of water to help them grow as it is crucial for your plant health. The correct watering frequency and type of watering system for your cannabis plants will vary depending on the growing medium. Overwatered plants can lead to root rot which will make your plant leaves turn brown and yellow and fall away. Underwatered plants will lead to a nutrient deficiency which will eventually hurt your plant and kill it.

If watering is too much for you, it could be beneficial to invest in self-watering containers which release a perfect amount of water every time without human interaction preventing overwatering or underwatering. You should also make sure that you PH your water before watering and check the soil to make sure that it is dry. PH your runoff water too to make sure your growing medium isn’t affecting PH levels too much. Thank you for reading our article, should you have any further questions see our articles regarding nutrient lockout, ppm, and PH.

To learn more about growing cannabis at home consider checking out our guides on: Getting Started, Troubleshooting, and Optimizing your Grow or search our Knowledge Base.

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