How to avoid stretching cannabis plants

How to avoid stretching cannabis plants
Steven Voser

Stem stretching will result in taller and weaker stems. If you want sturdier plants, please read our article about how to avoid stretching plants.

One of the potential problems, that cannabis growers face, is stretching stems. This phenomena occurs for numerous reasons. One of which the grower has very little control over: Genetics. For example, some sativa strains reach for the sky and grow to massive heights both indoors and outdoors, making stem stretching an inevitability.

However, with strains that are less prone to stem stretching, there are several ways to prevent or reduce it from occurring.


This so called stretching is really a growth spurt, that plants usually go through during the vegetative phase and also early on in the flowering phase. Not all growers are opposed to stretching, as it can be seen as a useful factor in ensuring the even distribution of flowers over a plant.

Also, stretching early in the vegetative phase may be a factor, that acts against bud rot in strains, that have a tendency to be weak against it, as the distance between flowering points may reduce humidity.

However, stretching isn’t all good. Stem stretching means a taller plant with a weaker stem. If your goal is to fully load your plants with large, towering buds, it will be susceptible to bending and damage if the load gets too much.

This can obviously end very badly for both the plant in question and the grower if no external support is used. Another downside to stem stretching is that certain plants will outgrow their designated grow space and become limited by the ceiling.

Let’s take a look at some ways to prevent or reduce stem stretching.


Air circulation may act as a small, but positive stressor, that might reduce stem stretching. Adequate air circulation will blow against the plants and force the development of stronger and possibly wider stems as an adaptation.


If you plant your crop too dense, eventually overcrowding will take hold. As your plants start to develop leaves, they will form a layer, that obstructs light from accessing the lower regions of the plants.


Some strains are genetically very short and compact, but still more than capable of pumping out some good size and excellent quality buds. Indica strains bare the characteristics of being shorter and more bush-like in nature, whereas sativas grow extremely tall in some cases. An autoflowering indica strain might be the best choice when wanting to reduce stem stretching.


Different wavelengths of light affect the growth of cannabis plants. Yellow and red light sources are often used during the flowering stage of the grow cycle, as they encourage plants to grow tall.

However, blue light is primarily used during the vegetative phase, as plants react by growing shorter with bigger leaves. Therefore blue light is optimal when it comes to the prevention of stem stretching.

Inadequate amounts of light will also lead to stem stretching, as seedlings will keep growing taller and thinner in an attempt to grow closer to the light source, so make sure your plants are receiving the proper amounts of light at each stage in the grow cycle.


Controlling the difference between daytime and nighttime temperature within the grow space will allow prevention of stem stretching. The closer these two temperatures are, the closer the internodes of the plant's stem will be. This means a shorter and stronger stem.

Steven Voser
Steven Voser

Steven is a long-time veteran of cannabis journalism, having delved into every aspect of the subject. His particular interests lie in cannabis culture, the emerging science of cannabis, and how it is shaping the legal landscape across the globe.