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How to water marijuana plants in soil

First of all, you should know that choosing the type of soil is very important; for this reason you should look for a light, airy soil that can retain sufficient amount of water. The key is to find the balance: neither too much nor too little, the right choice basically depends upon every grower and his/her feeding schedule.

To improve your substrate in terms of water retention, you should use perlite and coco fibre. The proportions of these elements are also up to the grower, but often range from 10 to 20% of perlite, and 10 to 30% of coco fibre.

Most soil bags sold at grow shops already contain these materials with a pH suitable for growing marijuana. Philosopher Seeds highly recommends choosing these ones instead of buying substrate from the usual garden centre.


Watering Sugar Pop from Philosopher Seeds

How to water cannabis plants in soil?

One of the most common mistakes of novice growers is to water their plants too often. To do it properly, you should water and wait for the soil to dry properly before watering again. The time between each watering depends on the size of the pots, the moisture in the air, the water retention capacity of the substrate, and finally, the age and needs of the plants in each stage of their development. A plant in its growth phase will not have the same needs as one in full bloom.

Therefore, it is best to wait until the soil is dry on its surface to water again and, in order to meet the needs of your plants, check the weight of each pot. But be careful! The surface may be dry, but if you hold the pot with your hands, you may notice that it might not need any more water and you can wait a little longer.

For proper watering of marijuana plants in soil we always recommend that you carefully scrape the top layer of soil several times before watering. A first go should get the substrate moist again: this should be done once or a few times until reaching the water saturation point in the pot. You can also follow these guidelines when growing directly in the ground outdoors.

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Scraping the soil smoothly before watering

Marijuana likes water in large amounts but not too frequently.

Soil is a substrate that needs time to absorb water. Using trays under the pots will allow the water drained during the irrigation to be absorbed by the soil within a few hours thanks to capillarity. Watch out! Make sure that you don’t leave them soaking for too long. If water still remains after several hours, empty the tray.

When grown directly in the ground – for those who are lucky enough to grow outdoors – you can spread straw on the soil around the plant during the warm summer months so you won’t need to water as often. This technique is not suitable indoors.

To avoid excessive washing of the soil, avoid pouring too much water (when drains through the holes), as fertilizers would flush away with the water and you would end up with a nutrient-poor substrate.

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Watering a Guayita marijuana plant

Excess water in marijuana plants

The marijuana plants’ roots need water as well as oxygen, so you should be careful not to water excessively as it could suffocate their roots and thus kill or slow the overall development of the plant. The first symptoms of excess water in marijuana are the wilting and discoloration of its leaves.

To avoid excess water in the substrate, the only option is watering when it is completely dry. The plant will recover soon and continue its developing.

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Marijuana plant with excess water (Forum Cannaweed; User: SILVERHAZE57)

Lack of water in marijuana plants

Unlike excess water, water deficiency is noticeable and easy to diagnose in marijuana plants. Leaves are hanging due to the loss of tension and if the absence of water is prolonged, the lower leaves will turn yellow and the plant will eventually die.

To mend this mistake or accident, there’s nothing better than a good thorough watering. When growing in pots, properly watering a plant that has suffered from water deficiency may be complicated, as the soil is barely able to absorb water, which will drain of the pot’s walls. A good technique to do it is to immerse the pot in a bucket, bathtub or container filled with water until it starts to get wet again.

Cannabis auto-flowering strains generally need less water, although some photoperiod strains such as our Early Maroc are also very suitable for guerrilla growing due to the same reason.

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Cannabis plant with water deficiency first symptoms

Philosopher Seeds

Marijuana plant with water deficiency

What is the best time of day to water marijuana plants?

When growing marijuana indoors, it is preferable to water them when the lights are on. Watering before or just after they go off can cause a rise in humidity that could result in one of the diseases caused by fungi such as powdery mildew and downy mildew.

Outdoors, cannabis plants are best watered in the morning when nights are still fresh and plants are not too big, and at dusk when days are hot and plants have grown, so that the water does not evaporate during the day.

In any case, whether in soil, coco fibre, hydroponics, in pots, in slabs or whatever the medium, the cannabis plants’ roots don’t like water that is either too cold or too hot.

Cold water could cause a thermal shock, but hot water is not suitable either, as it does not have enough oxygen.

Water at room temperature is the best option for marijuana plants as well as letting it rest for a few hours before use, which will cause the evaporation of chlorine if tap water is used.
In soil, pH should range between 6.5 and 7 and EC (electric conductivity) should be between 0.8 and 2.0.

Here is a link to a post that will be of help: pH and EC when growing marijuana

If you want to know more about the correct way to water marijuana plants in soil, we invite you to read a very comprehensive Expert Roundup post: 49+ Gardening Experts Reveal The Best-Ever Tips For Watering Plants 2017

All the best!

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