How tall do cannabis plants grow indoors - tips for optimal height control in indoor growing

When growing cannabis plants indoors, controlling the plant height is crucial for a successful harvest. The size depends on various factors, such as the strain, the light, the nutrients and the cultivation method used. While Sativa plants often grow taller, Indicas remain more compact - ideal for smaller spaces. With techniques such as low-stress training (LST), topping and the ScrOG method, growth can be directed towards the width in order to utilise the limited space efficiently. Common mistakes, such as incorrect lamp spacing, over-fertilisation or changing the light cycle too late, can cause height growth to increase uncontrollably. But if you find the right balance of light, nutrients and training techniques, you can control the plant height perfectly and get the most out of your indoor garden.

What affects the size of cannabis plants when growing indoors?

The size of cannabis plants in indoor cultivation depends on several factors that can be controlled. In contrast to outdoor cultivation, where plants sometimes grow several metres tall, indoor cultivation is ideal for adjusting the height of the plants according to your own wishes. The most important influencing factors are

• Genetics of the plant: The strain is crucial! Sativa strains tend to grow taller and slimmer, while indica strains tend to remain bushy and compact. Hybrid varieties can have a mixture of both growth forms.
• Licht: The light source and the light cycle have a significant influence on growth. High-quality LED lamps and a well-adjusted lighting time (e.g. 18 hours of light and 6 hours of darkness during the growth phase) promote healthy height. The closer the light source is to the plant, the more compact it remains. Conversely, they grow taller when the light is further away.
• Nährstoffe: The right nutrients in the right quantities can promote growth. Nitrogen-rich fertilisers support the growth phase, but over-fertilisation can also inhibit growth. The balance is crucial here.
• Topfgröße: The available root space influences the height of the plant. Plants often remain more compact in smaller pots, while larger pots offer them more room for growth.
• Training techniques: Methods such as LST (low-stress training), topping or the use of netting (Screen of Green, ScrOG) help to control the height and make the plants grow bushier. The training ensures that the plant directs its energy into the side shoots and does not just shoot upwards.

The size of the cannabis plants is therefore no coincidence, but the result of various growing conditions that can be specifically controlled. Anyone who masters indoor cultivation has full control over the plant height!

Average size of indoor cannabis plants

The average height of indoor cannabis plants varies depending on the strain, cultivation methods and the conditions used. In general, indoor plants remain significantly smaller than their outdoor counterparts, as available space is often limited and various techniques are used to control height.

• Sativa-Sorten: These varieties are known for their tall, slender growth and can grow up to 1.5 to 2 metres tall under ideal conditions. As they are normally limited in indoor cultivation, they usually reach a height of around 1 to 1.5 metres.
• Indica-Sorten: Indicas tend to grow more compact and bushy. They are perfect for indoor cultivation as they often reach a maximum height of 60 cm to 1 metre. Their denser growth makes them ideal for smaller spaces and cupboards.
• Hybride: Most modern cannabis strains are hybrids that contain characteristics of both sativa and indica. Depending on the dominant genetics, their heights vary greatly, but usually between 1 and 1.5 metres.

Indoor cultivation allows you to control the plant height relatively well. The aim is often to keep the plant as compact as possible and still achieve a high harvest. With the right training techniques and optimal lighting, the yield can be maximised without the plants growing too tall.

Top 3 indoor cannabis strains and their maximum height

Not all cannabis strains are equally suitable for indoor cultivation. Some grow particularly compact and are therefore ideal for limited space. Here are three popular indoor strains and their average growth size:

• 1. northern lights: One of the best-known indica strains, perfect for indoor cultivation. Northern Lights is known for its bushy growth and short height. Under optimal conditions, it reaches a height of around 80 to 120 cm . Its compact growth behaviour makes it ideal for smaller grow rooms and cabinets.
• 2nd White Widow: White Widow is an indica-dominant hybrid that is valued for its robustness and compact growth. Indoors, it usually reaches a height of 60 to 100 cm . With the right care and a little training, you can expect a dense, bushy plant with a high yield without growing excessively tall.
• 3rd Blue Dream: Blue Dream is a sativa-dominant hybrid that can grow slightly taller than the other two strains. Nevertheless, in indoor cultivation it remains with a height of 120 to 150 cm manageable. With a little training such as LST (low-stress training), you can also control the height of this variety and increase yields at the same time.

These varieties are popular options for indoor cultivation, as they are easy to control and produce a large harvest at a relatively short height. If you are looking for a variety that makes the most of your indoor space, these three varieties are a good choice!

How to control the height of indoor cannabis plants?

When growing indoors, controlling the plant height is crucial in order to make optimum use of the limited space. A few effective techniques can be used to control the growth of the plants.

A tried and tested method is the Low stress training (LST) . The branches of the plant are carefully bent down and tied up to promote flat, bushy growth. This technique ensures that the light is evenly distributed to all parts of the plant, causing it to grow in width rather than height. As more buds receive direct light, LST often results in higher yields.

Another option for height control is the so-called Topping . This involves cutting off the top of the plant, which limits vertical growth. After pruning, the main shoot splits into two new shoots, resulting in a wider growth habit. This method is ideally used early in the growth phase to allow the plant to grow bushier from the start.

The Screen of Green (ScrOG) method is very effective. With this technique, a net is stretched over the plants through which the shoots grow. This restricts vertical growth and allows light to reach the plants more evenly. ScrOG is ideal for maximising yields from a limited cultivation area, as the shoots are distributed and supported horizontally.

The light cycle also has a major influence on plant growth. During the growth phase (vegetation phase), the lighting should be set to 18 hours of light and 6 hours of darkness. To limit the height, the flowering phase (12 hours of light, 12 hours of darkness) can be started earlier. This keeps the plants smaller as they have less time to shoot upwards.

The choice of pot size also plays a role in height control. Smaller pots limit the space for root growth, which means that the plant remains more compact overall. Finally, the correct supply of nutrients is also important. A controlled amount of nutrients, especially nitrogen, during the growth phase can slow down height growth so that the plants do not grow too tall.

With the right combination of these techniques, the plant height can be effectively controlled. This makes it possible to grow healthy, high-yielding cannabis plants even in small spaces.

Optimum height for indoor cannabis plants

The optimum height for cannabis plants in indoor cultivation depends heavily on the available growing space, the light source and the grower's individual preferences. As a rule, however, the ideal plant height is between 60 cm and 150 cm. Within this range, the light can be utilised effectively and the space can be used as efficiently as possible.

In smaller grow rooms or cabinets, a height of 60 to 100 cm is ideal. This compact size enables efficient illumination of the plant and prevents it from growing too close to the light source, which could lead to burns. Indica varieties are particularly suitable for this height due to their natural growth.

In larger spaces, such as in a tent or a specially equipped grow room, the plants can also be allowed to grow to a height of up to 150 cm. This greater plant height is particularly suitable for sativa varieties and hybrids. However, care should be taken here to ensure that the lighting system is strong enough to provide sufficient light for the lower parts of the plant. Otherwise, the lower leaves and buds may receive less light, resulting in a lower yield.

In addition to the right height, the density of the foliage also plays an important role. The denser and bushier the plant is, the more light it can absorb for photosynthesis, which has a positive effect on yield. It is therefore important to use techniques such as LST, topping and ScrOG to promote growth in width and maximise the light yield.

Ultimately, the optimum height is a compromise between available space, light output and the desired yield. Keeping an eye on the plant height and adjusting it regularly is the key to a successful indoor grow.

Common errors when checking the plant height

Controlling plant height when growing indoors can be difficult, and there are some common mistakes that can affect growth:

• Incorrect distance to the light source: A common mistake is to ignore the distance between the lamp and the plants. If the lamp is too far away, the plants will stretch upwards to reach the light. Too close a distance, on the other hand, can burn the leaves and inhibit growth. The distance should be adjusted regularly depending on the lighting used to ensure optimum growth.
• Over-fertilisation: Too many nutrients, especially nitrogen, cause the plants to shoot up uncontrollably. The result is a tall but weak plant with few Flowers. Therefore, the nutrient supply should be carefully dosed and only administered in the appropriate amount.
• Missing training: Methods such as topping, LST or ScrOG are often not used or used too late. If these techniques are used early in the growth phase, growth can be directed towards the width and a more compact plant can be obtained. However, if these methods are applied too late, their effect is limited.
• Unsuitable pot size: Pots that are too large encourage root growth and thus the plant's height growth. Smaller pots help to control growth by limiting the root space. However, it is important to find the right balance, as pots that are too small can weaken the overall growth of the plant.
• Late changeover of the light cycle: Initiating the flowering phase too late will result in the plant continuing to grow in height and possibly outgrowing the available space. Switching the light cycle to 12 hours of light and 12 hours of darkness in good time helps to stop height growth in good time.

If you avoid these mistakes, you can effectively control the height of your indoor plants and get the most out of your growing space.

Conclusion

The size of cannabis plants grown indoors depends on various factors such as genetics, light source, nutrients and the training techniques used. While sativa strains tend to grow taller than indicas, growth can be controlled using techniques such as low-stress training (LST), topping and the ScrOG method. The optimum plant height is usually between 60 and 150 cm, depending on the available cultivation area and light output.

With the right combination of training, light management and root zone control, growers can effectively control the height of their plants. Common mistakes, such as incorrect lamp spacing, over-fertilisation or changing the light cycle too late, can be easily avoided by following the most important principles of indoor growing. With the right care and a trained eye on growth, nothing stands in the way of a successful harvest in your own indoor garden!