What to do when cannabis plants don’t grow or when the growth is stunted 

What to do when plants slow down or get stuck

Modified on: 29/07/2021

Find out how to identify the causes of stunted growth in cannabis plants and how to correct them.

It can be challenging to determine the causes of this phenomenon, even if the plant concerned is a cannabis plant.

It could be insufficient or excessive feeding, lousy lighting or who knows! Maybe the marijuana seeds are the problem as it is not always easy to find quality ones.

In this article, we want to help you understand why the plants are not growing and how you can remedy this. Note, however, that the cultivation of cannabis in the UK is illegal.

Here is what happens when the plants do not grow or grow too slowly.

Why don’t your cannabis plants grow?

When a cannabis plant does not grow or grows only very slowly, there is always a reason behind.

If you are not a cannabis expert, it can be challenging to understand if it is environmental factors, if there are problems with nutrition or perhaps light and temperature, especially if the plant’s growth stops suddenly or at the beginning of the harvest.

Plant with stunted growth after sowing.

Many people wonder what to do with plants that do not grow tall, how a self-flowering plant could block itself from flowering and how to fix this.

When faced with this type of problem, it is essential to have a general idea of the situation. It would help if you tried to have some data at hand and, in particular, to clarify what you have done before that.

With the list of cases and remedies that follo, it will be easy to understand whether a plant with reduced growth has suffered damage or whether the problem is due to the cannabis seed.

Let’s start with the former reason.

Read also: Excess fertiliser and cannabis: how to detect the problem (and how to solve it)?

Slow growth? Pay attention to the seeds’ quality.

If the cannabis crop grows slowly or too slowly when using auto-flowered or feminised seeds, it usually depends on the poor quality of the seeds you purchased.

It is not only crucial that you opt for good genetics. It is also essential to avoid seeds that are too old.

For example, BSF cannabis seeds you will find for sale on SensorySeeds.com have been selected for quality and age, while the seeds that are sometimes bought without too much attention, perhaps belong to slow strains that cannot guarantee a good yield.

The secret is to count on a reliable seeds bank.

Poor lighting can block or slow down the growth of a plant.

In addition to carefully choosing good cannabis seed genetics, it is also essential to pay attention to the plants’ light intake. Light is a fundamental element that regulates various developmental processes and can lead to stunted plant growth, whether it is low, too high or wrong.

If you believe that your cannabis plants do not receive enough doses of light, the solution to indoor growing is to move the lights closer to the apical part of the plants. On the other hand, it is necessary to place the plants in a brighter and sunnier environment in outdoor cultivation.

Excessive exposure can also cause stress to the plants and slow growth, especially in young plants.

It is important not to rush and respect the rhythm of the plant not pushing its growth by methods that may be counterproductive. To reduce the time from sowing to harvesting, you can opt to buy fast-flowering seeds to shorten the date of the first phase.

This said, if you think that your cannabis plants in indoor cultivation are subjected to high doses of light, it is best to move the lamps away from the apical parts of the plants and reduce intensity. Outdoors, likewise, it is advisable to move the plants to where the light is less direct and more diffuse.

Plant with stunted growth from too much watering.

Plant with atrophied growth due to too much water.

However, in a plant with atrophied growth, the motivation often falls on excessive watering.


When marijuana plants are given too much water, this can lead to the rotting of the roots with the multiplication of fungi and other micro-organisms, and nutrient defects.

If the plant is not healthy and does not receive the proper diet, it is expected not to grow as it should.

Mainly when excessive water damages the roots, it affects the oxygenation of the plant and thus slows down the metabolic functions so that the growth of the plant not only could slow but might definitely stop.

Ideally, a plan that is adapted to the plant’s growth phase should be followed. You should also check if the soil remains too wet and cannot dry out between waterings.

Plant malnutrition: growth slows down when nutrients are too little or too much

To thrive and grow steadily, cannabis plants must have all essential nutrients.

The usual soil can only guarantee these nutrients for 3 or 4 weeks, after which fertilisers must be used. In this sense, it is necessary to be careful with the doses. Indeed, cannabis plants cannot get rid of excess nutrients, which can lead to poisoning.

On the other hand, if nutrients are scarce, growth is naturally slowed down by the lack of “fuel”.

Parasites and insects: if the plant does not grow because it is exploited and damaged.

After all, insects and pests can be the cause. Some feed on sugar, some on the plant itself, and some damage the plant so much that growth is stopped.

In this case, it is essential to intervene as soon as possible by identifying exactly which enemies need to be controlled for the plant’s well-being.

Read also: The flowering stage for outdoor plants: the best practices!


You now know why sometimes you have to deal with plants with stunted growth.

If you are wondering how to accelerate the growth of your cannabis, the answer is to identify the problems mentioned above and apply the appropriate solutions.

We remind you that cannabis cultivation is not allowed in UK and Europe, but who knows … maybe this article could help you if and when the laws will change.

For now, buy the best cannabis seeds online and choose from feminised BSF seeds, BSF fast-flowering seeds and many other strains to collect them!

Visit SensorySeeds and add the seeds to your collection!

We are waiting for you.