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Cannabis plants that are too big in the grow box and what you can do about it

too big cannabis plants, grow tips, grow cannabis

Let's talk a little bit about too tall plants in your indoor garden. If you plan to be active as a basketball player, being a few inches taller can be quite beneficial, but with indoor plants it's a completely different story. Excessive plant height in the growroom can cause some serious problems. However, these are all problems that can be worked around and avoided. Learn more in the following article.

  • Growrooms or grow tents are usually and mostly limited in space. Most indoor growers have 1m² or 1.44 m² or less available with a height between 1.60 m and 2 m (or correspondingly less). Somewhere between the soil surface of the plant pots and the plant light is the maximum plant height. In many cases, the maximum plant height that the ladies are allowed to occupy is only 100cm or even less.
  • Tall plants have a higher center of gravity. When such a tall plant forms long inflorescences, it is easy for the whole plant to tip over - especially if the substrate is dry. In the worst case, a domino effect occurs and all the plants fall and knock each other over. It becomes difficult to let the substrate dry sufficiently before watering again, which makes sense and is important to avoid overwatering.
  • When cannabis plants grow too fast and sprout (spar) too rapidly, it often happens that the branches are correspondingly thinner and more delicate. In the flowering period, this circumstance can make it necessary to tie a lot and support branches to avoid breaking the branches or slapping the ground large clusters of flowers.
  • The larger a cannabis plant is, the longer the path from roots to flowers. This poses two problems: first, the plant needs a lot of energy to form the long branches instead of spending this energy to form thick flowers; second, the plant needs a lot of energy to bring the water and nutrients to a higher level, to all branches and buds, against gravity.
  • CO2 is heavier than air and therefore present near the bottom in the grow box. This means that the roots of very tall plants receive more CO2 than the flowers and leaves, although it should be the other way around.
  • Very large and tall plants also cause longer shadows and take away light from their neighboring plants.
  • For very tall cannabis plants, the distance from lower flowers to the light (to the light source) is much greater compared to smaller plants. According to the principles of light intensity in cannabis cultivation and the distance squared law, the number of lumens reached decreases rapidly with increasing distance from the light. Higher branches, leaves and twigs in large plants will obscure and take light away from the branches and flowers below, much more so than is the case with small or medium sized cannabis plants. The only light that reaches the lower branches through the dense leaf layer is dark red light (at about 760 and 800 nanometers). Dark red light activates phytochrome, which signals the lower branches to stretch to reach more distant light, further exacerbating the problem.

Indoor large cannabis plantsSafe ways to control the height growth of cannabis plants

In the following, we would like to introduce you to some possibilities to limit the height growth of cannabis plants in indoorgrow and to keep the internode distances short. By combining different methods, a reliable control of the growth structure is possible.

1. regulation of the temperature

The growth activity of many plants including the marijuana plant is influenced and co-controlled by temperature and temperature differences. Internode spacing of cannabis plants can be significantly influenced by temperature control. Internode length is directly related to the difference between day and night temperatures.

The warmer it is in the grow box during the day compared to the night temperature, the greater the internode length will be (day = when the lamp is on). The reverse is also true. The more the daytime and nighttime temperatures are apart, the shorter the internode spacing will be. This means that if the temperature drops too much in your grow box at night (lamp off), this can become a problem and plants will sprout up more because of it.

The ideal indoor growing temperature during the day, when the lamp is on, is between 21° and 25° C (24° C is best). This temperature should not be exceeded or fallen below. At night, the temperature should then not drop below 21° C to avoid too much internode spacing.

When the light cycle is brought to 12/12, the night temperature is initially raised to the same temperature as the day temperature, but not above 25°C. To keep the night temperature at the desired level, space heaters, grow box heaters and thermostats are used especially in winter. In warm countries, air conditioning and coolers must be used in summer mostly for indoor growing to keep the temperature at the desired level and avoid overheating.

Bar heater

 

A rod heater for the Grox box can be operated with a thermostat. This makes it easy and convenient to keep the temperature in the grow box constant even in winter.

 

 

During the first 2-3 weeks of the flowering phase, most strains start to lengthen their internode spacing. This makes it very important to control the temperature especially in this phase, because now the framework for the future flowering is formed. First, in the first 2 weeks of flowering, the night temperature is increased to the day temperature. After this time window, it is lowered again to 21°/22° C at night, because the plants are simply happiest with this. The temperature at night should generally always be slightly lower than the daytime temperature. If the daytime and nighttime temperatures were to be constantly set at the same level for a long period of time, this could result in yellow decolorized leaves (leaf chlorosis), among other things.

The final size of the buds is determined to a large extent by the average day and night temperature in your grow box. If the temperature is below 24° C during the day and below 21° at night, this can already cause losses in the size of the buds and thus the yield.

Once the flowers have reached optimal size and you have started flushing (omitting all fertilizers and additives from watering), you may consider dropping the temperature to 17-19° for the last week or two before harvest. This intensifies the color spectrum of many strains and, especially for many purple strains, causes leaves and flowers to turn an intense and bright red, brown, bluish or even purple color. This temperature drop activates anthocyanin production, which enhances the color of the flower clusters and makes for visually beautiful buds, especially in the variegated strains.

2. light intensity

Plants grow and stretch because of the plant hormone gibberellin. This also causes larger, more curly and faster cell growth between the nodes when plants are exposed to improper and insufficient light. To avoid this, you must see that you always use a sufficiently intense plant lighting with the right spectrum. See more at The right light for cannabis plants. The light should be as close to the plant tips as possible without burning them.

With sodium vapor lamps, a certain distance should be kept between the tips of the plants and the light, because they get very hot and can otherwise cause burns to the plants. The minimum distance you have to keep with sodium vapor lamps you can find here here. At the same time, a sufficiently powerful fan must always be used, because otherwise it can lead to overheating at the tips of the plants and in the box in general. In any case, it is also important not to increase this minimum distance (not at all), because this would also lead to stunted plant growth and small buds. You should see that all plants are well under the light so that none of them has to stretch to get to the light.

Luxmeter from VDL

To make sure your plants are getting enough light, use a light meter.

3. air movement

Oscillating fans in the plant room simulate the wind as it occurs in the wild and move leaves and stems. This movement also helps to prevent excessive height growth, because the plants are busy strengthening and repairing cell walls through the movement and therefore stretch less in height. In addition, oscillating fans ensure that CO2 is swirled up from the ground and pest infestations are reduced.

4. choose the right cannabis strain

the right cannabis strain

The cannabis strain you choose for your indoor grow has a huge impact on how your plants will grow later. The growth structure and height growth of a plant is mainly determined by genetics. Therefore, it is recommended for indoor cultivation to choose rather small, bushy growing varieties that are particularly suitable for indoor cultivation. There are countless very interesting strains for this purpose. Some examples of short growing strains are:

However, you can get just about any cannabis strain to grow bushy and keep it small with the appropriate training methods. Pure sativas are not really suitable for indoor cultivation and are more recommended for professionals, they also have a very long flowering time and are therefore uneconomical indoors. However, there are many hybrids that are sativa dominant and bring everything of a good sativa and still do not become trees in your grow box, but keep a moderate height. Indicas grow basically bushy and rather short. They are therefore always a good choice for indoor growing. Also autoflowering cannabis stra ins generally keep a manageable size and are therefore cultivated indoors by many growers.

5. topping

Topping for cannabis plants

Topping (= cutting off the uppermost shoot tip, see also Topping) is best done when the plants are still young and have only 3-5 nodes (pairs of leaves). Topping involves snipping off the top newest nodes on the main stem. This causes the cannabis plant to form two new main shoots and put its energy into them. These two main stems can be easily tied down and/or spread apart to form a V. If these two main stems are topped again about 2 weeks later, you get 4 colas.

The topping causes the cannabis plants to grow bushier later and the energy is put and distributed more throughout the plant. The background is auxins (plant hormones), which are located in the topmost tip of the main stem and control a continuous growth upwards. If this (this) top tip is cut, the auxin concentration is distributed more to the other branches, which in turn causes a bushier, shorter and more stocky growth.

Fimming is a similar and also effective method of limiting the height of plant growth and influencing the growth habit. In the so-called fimming or short FIM (the word comes from "Fuck I missed") is not the complete shoot above a nodie cut, but only about 3/4 of the freshly growing shoot pruned. This has the effect of widening the crown with many branches. See more at Fimming.

Fimming cannabis plants

6. low stress training

Super Cropping

Super Cropping

Low-stress training methods are low-stress plant training methods to control cannabis plant growth and increase yield. Low-stress methods include. , tie-down, Working with a planting net (SCROG) and Supercropping, which does not require cutting off parts of the plant and is therefore gentler on the plant. Super-cropping, as well as down-tying, is done with flexible, soft and fresh branches, not woody ones that are older and in danger of breaking or splitting when bent or kinked. When plants are manipulated in their growth structure with down-tying or super-cropping, they become bushier and develop more horizontally instead of vertically.

Bending and tying down, as well as other low-stress methods, offer very good and versatile ways to maximize the amount of marijuana harvested when there is little vertical space.

Supercropping: Supercropping involves bending flexible branches slightly without breaking them. Thick nodes form at these points, which can supply the buds with more nutrients.

Super Cropping, Cannabis Grow

Tying down is a gentle and effective method to control and limit height growth. All branches that are higher than the rest are tied down and thus a horizontal growth structure is achieved. At the same time this has the advantage that all flowers are evenly lit, similar to super grogging, and thus grow nicely tall. The plants are thus stimulated to develop their growth more in the width and they automatically grow less in height.

Tie down cannabis plants

Many growers want to avoid the typical Christmas tree growth of indicas indoors, because it is difficult to do so with all the flowers evenly intense lighting, and prefer to cultivate and train plants so that they form a flat carpet of lush and thick flowers. With a Plant net this can be easily achieved.

PFlanzen net, Scrog

7. pot size

If cannabis roots don't have too much room in the plant pot to expand their roots, the plants will also stay smaller. Basically, smaller pots make for smaller plants. Therefore, a good way to control the height of the plants is to use smaller pots, especially if the space for the grow is very limited. For automatic strains, i.e. auto-flowering cannabis strains, size control with small pots should be avoided. With these strains, bumping the root against the pot will result in significantly smaller yields.

the right pot size for cannabis plants

8. initiate the flowering earlier

Initiate cannabis flowering early

For strains that are known to have a tendency to grow taller, an effective way to limit height growth is to get the plants to flower earlier, i.e. switch to the 12/12 cycle earlier. Especially with sativa-rich cannabis strains, this approach makes sense. If flowering is already initiated after one to two weeks of vegetation, depending on the variety, the plant will end up with a much lower height.

Note: Small plants also produce smaller yields, so to achieve similar yields as with large plants, you need correspondingly more of them.

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