Watering cannabis - Everything you need to know

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Cannabis gießen - So Cannabis Überwässerung verhindern

When growing cannabis plants, many neglect the issue of watering cannabis. Proper watering of your plant is important, however, because over- and under-watering can significantly harm plant growth. Most grow problems can be attributed to improper watering. Cannabis overwatering in particular is a common problem, so you can remember, less water is more! Everything you need to know about watering cannabis can be found here in our blog article. If you are using our Bonsanto Growbox for cultivation, please read our growing guide on our website first.

Table of contents

Why is watering cannabis important?

Since cannabis plants are 80-90% water, it stands to reason that you need to water the plant properly, using good quality water. Water contains important minerals and nutrients for your cannabis plant. In addition, water is important for the process of photosynthesis, it cools the cannabis plant and supports healthy plant growth. Even before the seeds become seedlings, the correct water ratio must be ensured, you can read more about this in our blog article Instructions germinate hemp seeds .

Cannabis gießen - Alles was du wissen solltest

When to water cannabis?

A simple rule when watering cannabis is to always water when the soil is relatively dry. To do this, simply use your finger and stick it into the soil a bit to determine if the soil is dry or moist. If the soil is dry, it should be watered. If the soil is still moist, wait to water the cannabis. Generally speaking, when the top 1-2 cm of soil is relatively dry, it is a good time to water cannabis. If you don't want to use your finger to measure, you can also lift the pot. Watered soil weighs a lot more, so the pot should have a higher weight. However, this technique is more complicated than the finger method.

Regarding the optimal time to water cannabis, we advise you to water your cannabis plant before turning on the light when growing indoors, e.g. in the Mini Grow Box by Bonsanto. This prevents the plant roots from burning under the light exposure. If you water the plant in the evening in the dark, the humidity in the grow box can increase too much due to the lack of light, which promotes the development of mold.

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How much water does cannabis need?

How much water your plant needs depends on several factors. For example, factors such as the stage of development of the plant and environmental conditions will affect the water requirements of your cannabis plant. If your plant is in the seedling stage of development, we recommend watering with a spray bottle. This will prevent the seedlings from being soaked in water and damaged by the water spray. Developed cannabis plants, on the other hand, have a higher water requirement than seedlings, so you can put the spray bottle aside at this stage of development. Generally, the larger the plant, the higher the water requirement. For growing plants, we advise you to use one of the above methods and water only when the soil is relatively dry.

Another factor on which the water requirement of your cannabis plant depends is the humidity of the grow environment. If the humidity of the grow environment is high, the cannabis plant will require less water. If the humidity is low, you should water the cannabis more often.

Furthermore, when watering cannabis, the temperature in the grow environment plays an important role. A higher temperature means faster evaporation, which in turn means a higher demand for water.

Besides the temperature, your chosen lighting also affects the watering of your cannabis plant. If you use an LED lamp, for example the Full Spectrum LED lamp from Bonsanto, you will need to water your plant less, as LED lamps emit less heat compared to other lamps.

Obviously, the size of your pot also affects your plant's watering needs. The larger the pot, the more water you will need to use when watering cannabis.

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Cannabis Überwässerung

What properties must water have?

You can use different types of water for watering cannabis, such as rainwater, tap water, mineral water or filtered water. To find suitable water for your plant, you should consider the following criteria. 

If you use a Bonsanto grow box for cultivation , you have the great advantage that you do not need to pay further attention to this paragraph. The Bonsanto soil regulates the temperature, the EC and pH value of the water and the water hardness. So you don't need any measuring devices and you can use any water for watering your favorite plant. In this case, follow our Bonsanto growing instructions on our website.If you don't own a Bonsanto grow box or are interested in the theory, note the following: 


When watering cannabis, you should pay attention to the right temperature of the water. For cannabis plants, a water temperature of 20 degrees Celsius is best. You can use a thermometer to check the temperature of the water. Since 20 degrees Celsius is the room temperature in most cases, you can pour the water into a watering can or other container and leave it in the room for a few hours so that the water takes on the temperature of the room. If you use water that is too cold, the roots may suffer a shock.

pH value

Another important factor when watering cannabis is the pH of your water. The pH indicates how acidic or alkaline a solution is. Since the right pH helps your cannabis plant absorb nutrients, you should not use water with a pH that is too high or too low. Cannabis plants like a slightly acidic grow environment, so the pH of the water should be around 6.0 to 6.5. In Central Europe, for example, tap water has a pH of around 8 and is therefore too alkaline. In contrast, mineral water usually has too low a pH value and is therefore also not suitable for watering cannabis. If you want to adjust the pH of the water so that it is suitable for watering cannabis, you can use a pH regulating solution. 

EC value

The EC value of the water also contributes to healthy plant growth. EC stands for electrical conductivity and indicates the salt concentration in the water. It is important that your water contains neither too many nor too few salts to prevent over- or undersalting. The optimal EC value should be 0.2 to 0.5 when watering cannabis. At the beginning of plant growth, cannabis likes a lower EC level. Then, as the plant grows, it prefers a slightly higher salinity. If your tap water has an EC level above 0.5, it is best to filter the water to reduce the EC level slightly.

Water hardness

Another factor that influences the quality of water is the hardness of the water. The water hardness indicates the mineral content of the water. A high concentration of minerals is called hard water, whereas a low concentration of minerals is called soft water. For measuring you can use either a TDS or a conductivity meter. Soft water has a value of 70 - 140 ppm and should not be used for watering cannabis because it does not contain enough nutrients. This can lead to deficiency symptoms of the plant. The best water for watering cannabis is medium hard water, where your meter indicates a value of 140 - 210ppm.

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hanf überwässerung symptome

How do you recognize cannabis overwatering?

Cannabis overwatering is a problem that often arises in indoor cultivation. Overwatering your cannabis plant can cause the roots to drown, preventing them from absorbing the oxygen that is vital to your plant. Overwatering is much more damaging than underwatering and is difficult to correct. But how can you tell that cannabis is overwatered? One symptom of cannabis overwatering is firm and drooping leaves. If your leaves take on a yellowish color, this can be another indication of cannabis overwatering. Furthermore, you may experience slowed or absent plant growth.

What to do in case of cannabis overwatering?

If you notice these signs of cannabis overwatering, it is important to water your plant less and less often, and to ensure proper drainage of water from the pot. As a rule of thumb, when watering cannabis, about 20% of the water should drain through the pot. This suggests good drainage and loose soil, both of which are important factors for healthy plant growth. If you have only slightly overwatered your cannabis plant, you can give it time by letting the soil dry out. Wait until the plant has recovered and looks healthy again. If you have overwatered your cannabis plant, the only solution is to repot it. When repotting, inspect the roots of your plant and be sure to cut off any rotten roots. Plant your cannabis plant in a pot with new soil and wait with watering until it has recovered from the overwatering.

How to avoid cannabis overhydration?

An easy way to avoid cannabis overwatering is to choose the right grow soil. The Bonsanto Premium Grower is beginner friendly and has perlite, so overwatering is almost impossible and not so harmful for your plant.

How can you recognize underwatering?

While underwatering is less harmful to cannabis plants than overwatering, it should still be avoided. You can recognize an underwatered plant by wilted, brittle and drooping leaves and very dry soil. Furthermore, a bent plant stem and brown discolored leaves may occur.

What to do in case of cannabis underexposure?

To correct cannabis underwatering, soak your plant in water so that about 20% of the water flows into the saucer of the pot. Always water your plant when the top layer of soil is dry.

Cannabis gießen - Cannabis Bewässerungsmethoden
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What are the irrigation methods for watering cannabis?

Depending on your cannabis plant and your preference, there are several methods you can use to water your cannabis.

For example, you can water your cannabis plant manually with a watering can or hose. With this method, you should pour the water slowly into the pot and make sure to distribute it as much as possible so that it doesn't just collect in one spot. The advantage of this method is that you can control the watering well, but it takes more time than the other watering methods.

The second method of watering is called flood irrigation. Here you use a bowl, which is filled with water, placed under the pot. This allows your cannabis plant to absorb the water it needs from the saucer. This method is simple and fast, but unlike manual watering, it does not ensure an even distribution of nutrients.

For watering cannabis, you can also use the fast and easily controllable method of automated watering systems. These usually consist of a water tank or water pump with a timer. The disadvantage is the price of these irrigation systems. In addition, you need to regularly measure the EC and pH of the water. If you use the Bonsanto Growbox, you can save yourself the measuring here as well, because the Bonsanto soil regulates these values by itself. You can also find an inexpensive automated irrigation system in our shop.

In summary:

Through our blog article, you've learned how much water your plant needs, what factors affect your cannabis plant's water needs, and how to recognize and avoid cannabis overwatering and underwatering your plant. If you pay attention to the factors of good water quality and follow the rules of thumb of the right watering time, nothing should go wrong when watering cannabis now! If you use one of our Bonsanto grow boxes for cultivation, you save yourself a lot of work, because you don't need any measuring devices for checking the water quality. Everything you need to know about growing in the growbox, you will learn in the growing guide on our website. 

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