You have successfully germinated your cannabis seeds and are all set. Only a few months left until your first harvest!
Growing marijuana, however, is not always without its struggles. One problem that can arise during growth is that your seedling grows mainly in height and starts to stretch.
What is stretching?
When a seedling, or even a slightly older one, develops a long thin stem, it is called “stretching”. The cannabis plant does this in order to get closer to the light and in this way absorb more light.
The formation of a long and thin stem occurs mainly during the plant’s growth phase. Once flowering has begun, the growth of most cannabis strains virtually stops.
Sativa species in particular tend to increase in height somewhat during flowering. As young adult plants, Sativa species do have the tendency to stretch a bit more in size during the growth period.
What if stretching gets out of hand?
Stretching can also get out of hand. All stem and little leaf. What is the cause of this and what should you do if this happens to you?
The answer is not unequivocal. There can be all sorts of reasons why your cannabis plants become lanky. Therefore, this article will explain the most common reasons and offer a solution. We will start with the problems that long, thin cannabis plants (can) bring.
Problems with tall and skinny cannabis plants
- The stem becomes too weak – this can cause a plant to fall over or the stem to break.
- Problems with nutrients – stretched plants will put their energy mainly into growing taller when that energy could be better used for even growth.
- Burnt plants – tall cannabis plants are more likely to grow too close to the light source, putting them at risk of burning.
- Problems with humidity and temperature – stretching the stem can lead to problems with humidity and temperature.
Reasons of tall and skinny cannabis plants
There are several reasons why cannabis plants develop a long and skinny stature during the vegetative phase. You’ll see the most common reasons (and solutions) below.
- Grow lights are too high
- The used lighting is unsuitable
- The light source is too far away from the cannabis plant
- Light source is too weak
- Plants are too close together
- The plants are kept too long in the vegetative phase
Keeping the distance between the grow lights and the plants right is vital. Make sure the plants are not too close together in the grow tent and that the light source is not too far from the plants.
The type of lamp you choose also affects the stretchability of the stems. Orange and red lights are associated with long, thin stems, while blue light is better for thick, stocky stems. Metal halide lamps used during the vegetative phase, for example, also lead to shorter stems.
If your lamp is too high above your plant then your plant will start looking for the light with the result that your plant will grow mainly in height.
This is easily solved by hanging the lamp lower. The space between your lamp and the top of the weed plants needs to be reduced in this case.
Keep a close eye on the temperature however. If the lamp is too close above your plants it can damage the leaves. Keep the following rule in mind: if it is too hot for your own hand, then it is also too hot for the plant.
Also when the light source is too weak your plant will tend to seek the light and this problem is also easy to solve.
Use light with more power. The more powerful your light, the better a cannabis plant will grow. For example, if you plan to grow under a 40-watt energy saving lamp, your plant will undoubtedly stretch. If you want to ensure good growth, make sure there is enough power in the lamps to provide the plant with enough light.
You can pre-grow under adequate cool-white and warm-white fluorescent lights or under an HPS lamp designed for both growth and flowering.
In your research into why your cannabis plant is a thin, skinny, tall plant, you might come across the term ‘SARP’. A term which stands for Shade Avoidance Response Phenotype.
SARP is a “problem” that occurs when a plant stretches to reach the light that neighboring plants are blocking. This is because plants are aware of their surroundings and will respond accordingly if conditions are not right.
A cannabis plant really likes the sun. It is therefore important that your marijuana plant is in direct (sun) light as much as possible.
By placing your plants a little further apart the light can penetrate better and a wider growth will be motivated. A cannabis plant should not stand in the shade. This is also absolutely negative for the growth and flowering of your cannabis plant. If your plant is not placed in full light, the chance that it will stretch is very high.
Cannabis plants can quickly become too tall and completely take over the grow space. You can then apply drastic measures such as Super Cropping. However, it is much better to just not keep the plants in the vegetative phase for too long. Switch to flowering as soon as the instructions for your specific strain recommend it.
Buy Indica or autoflower seeds to avoid unnecessary stretching
As you’ve read, stretching is not necessarily a bad thing. It serves a clear purpose. Moreover, some strains will naturally stretch more than others. Unnecessary stretching can therefore be prevented in a simple way.