Do your cannabis plants have purple stems? Find out why

Written by on 9 July, 2020

Like a cannabis grower, it is very important that you constantly keep an eye on the development of your plants, and check the temperature levels, lighting and other factors from time to time to keep everything in order.

Marijuana plants in many cases show certain signs when something is not right, so it is necessary that you are alert to detect and correct any problems.

In this opportunity, we will talk about the reasons why a cannabis plant can have purple stems; situation that does not necessarily mean that there is some risk for the plant. Read on.

1) Genetic factor

As we mentioned before, is not very usual change you notice in your plants is a problem. For example, purple or purple stems that sometimes appear during the first days of the plant’s life in the apical zone are not always a cause of danger.

This can occur for genetic reasons in marijuana such as varieties with a properly purple genetics like Purple Afghan Kush or Purple Orange CBD or those that simply grow with the stems in this shade.

In this sense, if apart from the purple stems, the plant is in optimal conditions (with good growth, proper leaf shape, among others), it is essential not to make changes in one or two weeks for the plant to continue its process of adaptation to the environment.

2) Lack and excess of some nutrients

When the plants have purple stems accompanied by leaves with curled downward nerves of the same shade (even developing parts, are black), they may have a phosphorus deficit.

On the other hand, if you see plants with yellow leaves that then get darker, along with purple stems, your cannabis may need magnesium.

In this situation, you have to provide the plant with the necessary nutrient and it will soon recover and acquire its normal color.

It is important that you do not overdo the amount of nutrients you supply to your plants, as an excess of nitrogen can also produce purple stems and branches and thus other complications. Of course, you must be aware of other signs to correctly determine that it is an excess of nitrogen, and correct it before it is too late.

3) Environmental factors

It is necessary to observe the growth rate of cannabis. If you notice that it has slowed down it may be a sign that something is wrong.  You should check the temperature to which marijuana is exposed, because when cold weather invades the plant, it usually turns purple, affecting its growth and flowering.

Just keep the temperature at the right levels, which are around 20 °C (minimum) to 25 °C (maximum).


Learn more about the symptoms and signs that plants show when they have an excess or deficit of a nutrient, and you will be able correctly determine if that is what is happening to your plant and which nutrient it is. You will also be able to correct the problem and prevent marijuana from undergoing unnecessary processing.

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