When Cannabis Leaves Turn Yellow
30th April 2020

When Cannabis Leaves Turn Yellow

Elijah Farley
Hemp or cannabis plant is a tall annual plant which is either male or female, and is harvested in the fourth or fifth month. The alternately arranged leaves consist of five or seven leaflets that are green in colour.

Hemp, when used together with lime can be used to produce building materials. Some of the species of cannabis plant with less mind affecting components are used to manufacture paper. It is also used to clean out impurities in waste water and produce drugs useful medically. Creams, oil paints and bio diesel are produced from oil in the seed and stalk of the hemp plant.

Systems for growing the hemp or cannabis plant are the outdoor cultivation method and indoor cultivation method. Outdoor cultivation method is a cheap method that involves growing the plant on natural or manufactured soil either on an expanse of land or in pots. Hydroponic method of cultivation is an indoor cultivation method that involves growing the plant in a pot containing gravel that is frequently flooded with water and fertilizer.

The cannabis or hemp plant is trained using the trellising, defoliation, topping, pinching and low stress training techniques to increase their yield.

Buds of the cannabis plant are

Trellising is a process that involves the weaving of stems through the gaps in a vertical or horizontal framed screen. carried out to make full use of the growth space and light available to the plants.

Defoliation is the removal of small leaves from the lower part of the plant so that the plant can concentrate its growth effort on parts that have more light penetration. This increases the yield of the plant and encourages a dense and thick bud growth.

Pinching and topping are training methods that encourage an increased yield. Topping involves cutting off the apex of the plant to change the distribution of hormones and promote lateral growth while the plant heals. The stem is not broken in the pinching method but the destruction of the structural cells give the lower branches time to grow rapidly before the stem regains dominance.

Buds of the cannabis plant are bent and tied in a way that ensures light penetration which increases the yield of the plant. .

Excess light can also cause the

The hemp plant is stressed where there is a deficient or excess supply of nutrients and conditions needed for it to thrive. Nutrients such as Nitrogen, Phosphorus, Potassium, Calcium, Boron, Chlorine and Magnesium are needed by the plants to grow well. They also need a good temperature range, light, sufficient water and a basic growth medium.

A pH level of the growth medium that is not favourable to the growing cannabis plant can make it difficult for the plants to absorb nutrients from the growth medium used and therefore cause the leaves to turn yellow. Over watering can also result in a yellowing of leaves as roots cannot absorb nutrients easily from the growth medium.

Exhausting the nutrients available to the cannabis plant in its growth medium can cause nitrogen deficiency. Leaves at the bottom of the cannabis plant usually turn yellow and are easily pulled off when a nitrogen deficiency sets in.

Excess light can also cause the leaves of the hemp or cannabis plant to turn yellow. Leaves affected are usually closer to the light source and are not easily pulled out unlike those affected by nitrogen deficiency.


A lack of magnesium in the growth medium is a cause of the yellowing of leaves at the lower parts of the plant. The space between the veins and the edges of the leaf usually turn yellow but the veins of the leaf itself remain green.

Iron deficiency turn all new leaves of the plant yellow but older leaves do not change colour. Leaves affected become green again starting from the outer edges of the leaves of the plant involved.

Pests such as the larvae of fungus gnats which usually appear in over watered soil and feed on plant roots and spider mites can also cause an overall yellowing of leaves.

Normally, the leaves of the cannabis plant can also turn yellow when it is mature and ready to be harvested. Yellowing of the early leaves of the plant is also considered normal especially if they are not getting sufficient light. Adjusting conditions for growth as needed by the plant would be helpful in growing healthy leaves where yellowing is stress induced.


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