How to Deal With Stretching Cannabis Seedling?

Elongated and stretchy stems don’t provide a stable base for a seedling, which can end up affecting the plant throughout its lifecycle. Learn how to fix this and prevent it from happening again.

A seedling does not need any food for the first good few days of its life. From its genetics, it is already backpacking all the essential nutrients needed to embrace the miracle of life. Seedlings have a little reserve to help establish themselves in their growing environment.


There are several reasons why a marijuana plant may stretch. Sometimes there is nothing you can do to prevent a plant from creating tall stems regardless of your efforts to stop it.

Abnormal stretching in the seedling phase is a sign of stress. Here are just a few reasons why a seedling might stretch. Some are biological and others aren’t, however in all cases, the plant grows differently as a result.

  • Lack of nutrients in the soil
  • Unstable temperatures
  • Improper lighting schedule

There’s also the plant’s genetics. If a marijuana plant’s parents were originally grown indoors or if they promoted the growth of crowding plants, there is a chance that natural selection kept this trait in the seed’s genotype. But if those seeds were made by a ‘’Willy-nilly’’ crossing from hybrid plants, their offspring will be so variable that it will be hard to know what to expect. Keep in mind, some plants just naturally grow taller than others. One example of a strain that grows tall both indoors and outdoors is the tropical, landrace pure Sativa.

Light During The Seedling Stage

By far, the most common situation that causes seedlings to stretch and topple over is light deprivation. In the same way a taproot digs for water and nutrients, the top part of the plant will stretch vigorously if it is not receiving enough light. It is a survival mechanism. It will use up all its stored energy to rise above competing flora. In the case of indoor growing, there is no competition, but the seedling will perceive it this way. For instance, leaving the pot under a windowsill in the shade will likely trigger this behaviour.

Seedlings don’t require too much light to grow. In fact, a light, that is too strong, can sometimes do more harm than good in this early stage. Many cultivars grow seedlings under fluorescent light tubes, which are relatively weak and optimal suited for this purpose. Because of the rather weak fluorescent light it is normally recommended, that you place the fixture with the light as close as 5cm above your seedlings. Know that the further away your grow light will be, the more stretched-out and longish your plants will grow in their search for light. Avoid having your seedlings become too stretched-out, because they would then easily tip over. Find the best distance to the light for your seedlings so they won’t stretch too much.

For optimal seedling growth, get a grow light with a “cold” spectrum, that will be beneficial for early vegetative growth. These types of lamps have more blue in their spectrum as compared to flowering lamps, that will have more red.

As for the best light cycles for your seedlings, you can go with the common 18/6 light schedule, which is 18 hours of light per day, with a 6 hour darkness period, although some growers use 20/4 or even 24/0. You can experiment which light schedule would give you the best results.

Air Circulation

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.

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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.

Strain Choice


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.

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