Growing hemp is as simple as growing other plants. Just plant a seed and water it.

Every plant needs light, water, air and a substrate to hold on to in order to live, plus some nutrients. For the plant to thrive, all the elements must maintain a certain balance since both the excess and the lack of one of them would compromise its optimal development.

In general, it is recommended to apply all fertilizers very diluted to avoid overdosing. As already discussed in the article “Nutrients and micro elements in cannabis cultivation“, it’s much easier to correct a nutrient deficiency than an excess.

When growing in pots, to avoid the accumulation of salts, we must rinse the soil generously once every 4-5 weeks. We will water each pot with 2 liters of water (0,5 gallon) for each liter of soil. This will eliminate all the salts accumulated. This practice is particularly useful in areas where tap water is very hard, therefore with a pH above 7.4.



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Not all symptoms of a deficiency occur at the same time, and several elements are often missing at the same time. To remedy these deficiencies we must first rinse the soil in order to eliminate excess salts as explained above. Then it is watered with a fertilizer complete with microelements which will solve the deficiency.

In order for the cannabis plant to absorb nutrients properly, the substrate pH must be between 6.5 and 7 if grown in soil, and between 5.8 and 6.8 in hydroponics.

This is achieved by always adjusting the pH of the irrigation water within this range. There are several methods and tools to measure pH. We can buy specific products to raise or lower the pH of the irrigation water too.



Symptoms: the plant become a darker green color. In the beginning it grows very well. But over time the fertilizer builds up, the leaves start to burn at the tips and curl downward.

Solution: Wash the soil thoroughly to remove all excess fertilizer. The soil may need to be washed two or more times. When the earth is clean, you can start fertilizing again with greater moderation.


Symptoms: Plants turn light green and older leaves turn yellow. Growth slows down or stops. Symptoms are similar to those of nitrogen deficiency.

Solution: Fertilize the soil with a complete fertilizer with micro elements.


Symptoms: The ground is always wet. Mold grows on the ground or the stem of the plant begins to soften at ground level. Growth is slow and the roots grow poorly due to lack of oxygenation.

Solution: Plants need a dry period between waterings. Wait until the soil surface has dried before watering again. If the soil mix you use doesn’t drain enough you can add perlite, vermiculite, expanded clay, or sand to the mix.


Symptoms: The plant grows poorly and the leaves have withered. The land dries a lot between irrigation and irrigation. It has few leaves and they are small.

Solution: Whenever we water a plant we need to use a lot of water. With poor watering, some of the soil does not get wet well, and the roots suffer and die. The best way to make sure all of the soil in the pot gets wet is to water until the water starts flowing out through the pot’s drainage holes.


Symptoms: plants grow thin and elongated tending towards the light. In low light conditions, more male plants usually come out.

Solution: We will move the plants to a place with more hours of sunshine. Growing indoors requires more powerful lights.


Symptoms: Plants show deficiencies that are not corrected when we fertilize. There are traces of dried salts on the edges of the pot and on the saucer. The leaves are curved downwards as in the presence of an excess of fertilizer.

Solution: This is one of the most common problems among novice growers. When irrigation is poor and fertilizers are much, the salts that accumulate in the soil can kill the plant. The solution is to cleanse the soil with plenty of water. If the salts have accumulated for several months, we will wash the earth at least twice with two or three liters of water per liter of soil. If the problem persists, we will wash the earth again and not fertilize until the plant has recovered.



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Avoiding nutritional deficiencies is not really a difficult task. Just fertilize regularly with a complete fertilizer and make sure salts don’t build up in the soil. The vast majority of issues when growing hemp results from excess fertilizers and the consequent accumulation of salts in the soil.

When one is not sure whether the deficiency is due to an excess of salts or a lack of fertilizer, it’s better to cleanse the soil first, and then fertilize moderately with a complete fertilizer. The plant should be given the time to react and assimilate before taking further action.


Symptoms: Old leaves turn yellow and the tips burn. Growth is stunted and the plants grow thin. The color of the leaves turns pale green.

Solution: Add nitrogen to irrigation using specific fertilizers for green plants such as an algae extract.



Symptoms: leaves and stems turn dark. The growth of roots, stems and leaves is interrupted or stunted. The lower leaves fall off and the stems are brittle.

Solution: Fertilize with a high phosphorus fertilizer such as bat guano. All specific fertilizers for flowering plants are able to bring higher percentages of phosphorus.


Symptoms: older leaves turn yellow starting from the tips curving downwards. The young leaves are wrinkled and misshapen. Growth shoots die off and the stems are brittle.

Solution: Potassium is not always lacking but often fails to be assimilated into plants due to an accumulation of salts in the soil. There is no alternative but to rinse the soil thoroughly and fertilize with potassium-rich compounds only when the plant begins to show signs of recovery. Fertilizers for succulents are generally particularly rich in it.


Symptoms: Old leaves turn yellow between the veins and remain green overall. Normally they curl upwards and then degrade. The whole plant could turn pale in a few weeks and could perish if left unattended.

Solution: Magnesium deficiency is relatively common in cannabis cultivation as the plant requires high percentages that are often not present in common fertilizers. Magnesium can be supplemented separately using Epson salts (hydrated magnesium sulfate) in the proportion of one teaspoon per 4 liters of water.


Symptoms: iron deficiency is also usually due to excessive accumulation of salts in the soil or a pH of the same that is too high. This does not allow the plant to absorb it. The leaves turn yellow especially between the veins until they fall off

Solution: Like potassium deficiency, the solution is to rinse thoroughly with water only, “washing” the soil. The pH must be monitored and maintained in the optimal values.