How tall can cannabis plants grow?

Before you start growing cannabis, it is good to know how tall cannabis plants can actually get. Some strains can grow to be meters tall, while others remain smaller and more compact. Various factors influence the size of your plants. In this blog we explain what is going on and how you can influence this.

The height of cannabis plants

If you are just starting to grow cannabis, there is a lot to take into account. But in any case, it is important to take into account the question of how tall your cannabis plants should grow at most. Are you planting them in your backyard and don't want them to grow higher than the fence? Or are you growing indoors and preferring to keep them small and neat? Will the plants fit in your greenhouse or will they become giant bushes that grow much bigger than you expected?

It's nice to have control over the height of your plants. That's why we'll explain which factors influence the growth and therefore the length of cannabis plants. That way, you won't be faced with any nasty surprises.

Genetics

Of course, genes have a lot of influence on how tall cannabis plants grow. There are different strains (sativa and indica), crosses and in addition there are autoflowers. In general, you can say that sativa strains grow quite tall, sometimes up to 5 meters high. Indicas stay closer to the ground and grow to an average height of 1.5 to 2 meters. They look more like bushes. Autoflowers also usually do not grow higher than 1.25 meters.

Distance between plants

When plants are placed very close together, the phenomenon of stretching occurs. This occurs because the plants do not get enough light, because they are in each other's shadow. They grow fast, just to become as tall as possible. This results in long, thin plants.

Light

A lack of light can also lead to stretching. If you grow indoors and there is not enough light, you will see that your plants become long and lanky and stretch towards the light source in the room. Outside, this is less likely to happen, unless you put them too close together.

Size of the pot

If you put your plants in pots, it is important to pay attention to the size of the pot. If you use pots that are small, this will affect how big the roots can grow. This means that your plants will not grow as tall, but can also be used to limit the size of your plants. The larger the pot, the larger the plant will grow.

Humidity and temperature

Other factors that play a role in how tall cannabis plants grow are temperature and humidity. A higher temperature stimulates growth and optimal humidity is also important for good development of the plant. If these are not set correctly (especially when growing indoors), growth problems can occur.

Height of different strains

Are you looking for a cannabis strain that suits you? Then pay close attention to what is stated in the description. In most cases, the average height of the plant is stated there. This way you can take into account how much space you have. Feminized photoperiod plants generally grow taller than autoflowers.

Influence how tall your cannabis plants grow

How much space do you have available for your growing? That is your starting point when choosing seeds. If you are going to grow indoors, you should consider the size of the grow tent and the power and number of grow lights. In general, a height of up to 1.20 meters is the best size for indoor cultivation.

Plants can grow freely outdoors, but in most cases there are also plenty of reasons to limit the height. This is usually for discretion and protection ible space in the garden. You can then choose a species that naturally remains a bit smaller. If you do opt for a larger species, there are ways to control growth, both indoors and outdoors.

Pruning techniques

• A good way to control the growth of your plants is by pruning. With Low Stress Training (LST) you can control growth. You carefully bend the main stem and branches and tie them up. This gives you an even canopy and stimulates more lateral growth. Your plants will stay lower as a result, but at the same time they will also develop more buds.

Topping is another technique. Here you cut off the main stem, which gives the plants the incentive to grow in width instead of in height. Where the main stem is cut, two new stems will grow.

Grow lights

• With grow lights, you can ensure that your plants have enough light. Make sure that you set the light intensity correctly for each growth stage. This way, you prevent stretching, and you will keep control over the height of your plants.

Choosing the right pot size

• As mentioned, the size of the pots also affects growth. If you want to ensure that your plants do not grow too tall, choose a smaller pot. This limits root growth, which means that your plants remain somewhat smaller. You can use this technique both indoors and outdoors.

Pay attention to the flowering phase

• Switching to the flowering phase can be a good way to prevent your plants from growing too big. For example, after 2 to 4 weeks of growth, you can induce flowering. When growing indoors, you do this by adjusting the light schedule, from usually 18 hours of light and 6 hours of darkness, to 12 hours of light and 12 hours of darkness. When growing outdoors, this is a bit more difficult. Then you will have to provide more darkness yourself. You can do this by building a construction over your plants with a light-proof cover. This allows you to ensure that your plants are in darkness for 12 hours to initiate the flowering phase.

Disclaimer

The information in this blog is intended for educational and informational purposes only. Growing cannabis is subject to laws and regulations that can vary greatly per country, region or municipality. In the Netherlands, growing cannabis for personal use is permitted under strict conditions, but in many other countries this is prohibited and punishable.

We always advise you to consult local laws before deciding to grow cannabis. The author and website are not liable for any legal consequences or damages resulting from the use of the information in this blog.

Sources:

• Leafly - Cannabis strain database
  https://www.leafly.com/strains
  International source for information on strains, heights and properties.
  
  

• PubMed study on light and growth of cannabis plants
  https://pubmed.ncbi.nlm.nih.gov/30857076/
  Scientific study on growing conditions for cannabis
  
  
• Rijksoverheid - Cannabis and the law in the Netherlands
  https://www.rijksoverheid.nl/onderwerpen/drugs/cannabis
  Explanation of what is and is not allowed when growing cannabis in the Netherlands.