How to water cannabis plants in the soil

How to water cannabis plants in the soil

Beginning growers often wonder what is the best way to irrigate cannabis in the soil. It’s true that cannabis needs a lot of water, but it’s also true that it hates waterlogging, so it’s easy to make mistakes. Following these tips will ensure optimal growing results.

Cannabis is a plant that does not like constant watering. It is important to water the crop heavily and then wait until the soil dries out before watering again, either with fertiliser or tap water.

Use the following steps to calculate the amount of water needed per plant:

The volume of water required for each irrigation must be at least a quarter of the total volume of the pot or container.

• For a 1L pot, use 0.25L of water for each watering.
• For a 4L pot, use 1L of water for each watering.
• For a 12L pot, use 3L of water for each watering.
• For a 30L pot, use 7.5L of water for each watering.

Usually we need to water 2 or 3 times, slowly and evenly over the entire area, in order to adequately moisten the entire substrate. Place plates under the pots so that they are filled with water immediately after watering the plants; this water will be absorbed by the capillary in less than a day. It is also very important to use a good quality substrate, not only with good retention capacities, but also with good drainage ( our substrate should contain clay gravels, perlite and/or coir ).

After watering, you may notice that the pots/containers are now very heavy and difficult to move. You should now weigh the containers each day – you can do this with your hands. You can use a pot filled with dry substrate to compare the two weights. When they have lost most of their weight, it is time to water them again.

As a result, because water weighs much more than soil, a pot saturated with water weighs much more than another pot ready to be watered. With a little practice, you will quickly learn when is the right time to water your cannabis.

This technique is very easy and effective and is suitable for all types of potted plants! Using this method, you will probably water your plants once every 3-6 days. Some factors may require more frequent watering, e.g. small pots, dry and hot climates, sunshine, etc.

Drip irrigation does not give good results in soil and should only be used in exceptional cases (holidays). If you want a functional drip irrigation system, you should forget about soil and use any hydroponic substrate available on the market (coco coir, rockwool, clay pebbles, etc.).

What is the best water for cannabis irrigation?

You can use tap water if the EC value is <0.4. Otherwise, dilute it with clean water (EC = 0.0) such as rainwater or osmosis/demineralised water to get an EC value of around 0.3.

Cannabis plants do not like chlorine, lime (hard) water or other substances contained in tap water. We recommend allowing the water to evaporate all chlorine at room temperature (24 hours at rest).

• Osmotic water is ideal for growing cannabis if you add a few additives to it. This can be easily found in pet/fish shops or can be made using an osmosis system. We should add calcium/magnesium/trace elements as most fertilisers are made for use with tap water.

• Rainwater is also very useful, but it is recommended – especially indoors – to put it in the microwave for a few seconds to sterilise it from bacteria, eggs, fungal spores, etc.

• The pH value of the water must be between 6 and 7. If this is not the case, it must be adjusted with a pH tester and pH reducer.

Tips for watering marijuana

In the last weeks before harvesting, the water requirement of the plants decreases. Then we need to gradually reduce the amount of water with each watering, because if the substrate dries out for too long we can have fungus problems in the buds. In addition, a slight ‘water stress’ at the end of flowering increases resin production.

However, don’t forget to flush your plants with water (without any fertilizer) 3-4 weeks before harvest.

Apply fertiliser every two waterings or two out of three. Flushing the plants with water (or you can add enzymes or humic/fulvic acids) dilutes and ‘recycles’ those nutrients accumulated in the soil that can intoxicate the plants with cannabis.

Obviously, the larger the plant, the more water it needs. If you notice that a particular plant needs less water than others, you can reduce the amount of water for irrigation so that you can water all the plants on the same day. The same goes for plants that require more water than others.

Spraying plants with water causes them to have fewer roots, so avoid spraying more than 1-2 times a week. Because plants take up water from their leaves, they do not develop a nice root ball to find it in the soil.

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