My Cannabis Plants are Growing Too Tall!

So you’re growing your weed in your backyard and now it’s taller than the neighbours’ fence. It’s amazing to see your plant grow so huge but it can sometimes get out of hand and make for a time-consuming harvest.
Sometimes when we grow indoors our plants will grow quickly towards the light source. This might damage top leaves with heat stress as well as block light from the lower branches.

Indoors or outdoors, having a plant that is growing too tall can be a problem. Here are a few ways to avoid this and one method that can save your harvest.

Here I am next to a giant sativa cannabis plant. I’m about 5’11” so I’m guessing this plant is close to 9 feet tall!

This might attract the attention of neighbours, thieves, and even the police.
In many places cannabis plants must be grown out of public view.

Keep your plants short and you can avoid any unwanted attention and grow a better plant.

Super Cropping Cannabis

This technique can be a little risky but will immediately lower the height of the plant. Super cropping is a type of high-stress training where you bend the main stem 80-90 degrees. This damages the stock in such a way it creates a “knuckle”.

This high stress method can actually help give you bigger more potent buds. Cannabis produces THC as a defence mechanism against animals. When the plant is damaged it will focus energy on growing buds and THC.

I find the best way to do this is to pinch the stem and slowly wiggle it in the direction you want it to go. Bending a stem that is too thick or trying to do this too fast could break the stalk badly causing serious shock and potentially killing everything above the bend point.
If you do end up breaking the skin on the stalk it can be saved with a bit of tape. Black electrical tape works well to seal up the damaged stem. That tape can be removed a few weeks later.

You might also need to support the bent stalk with a lattice or string. The branch might snap from the weight of the top buds as they mature. The horizontal branch will grow upwards towards the light over time, so make sure you crop your plants short enough the first time.

Super cropping is normally used as a plant training method during veg to improve light coverage. That “knuckle” that forms helps strengthen the main stalk. This technique is not recommended to autoflowers because the stress will slow growth temporarily but it can be worth experimenting.

Topping / Pinching New Growth

While the plant is still in veg you can cut off the newest growth at the top of the plant. This is called topping and will create two offshoots. You can continue doing this as long as the plant is in veg. The plant will grow shorter and bushier. 

What’s happening here is the grower is playing with the natural hormones of the plant. There’s a hormone responsible for growing the top branch often called a cola. When the new growth is clipped that hormone is sent to the two new offshoots. Colas are also the largest bud sites on the plant, so more colas means more large bud clusters.

Placing a net over the plant will help spread out branches so they can get the most light possible. This is called scrogging. You can see many outdoor cannabis farms use this technique all around the world. Having shorter bushier plants makes them easier to maintain and harvest. Topping will also prevent your plant from looking like a Christmas tree peeking over the neighbours fence.

example of topping

This plant was topped. You can see the two new branches beginning to grow from the cut site.
You can learn more about topping and how to do it our What is Topping Cannabis article.

Shorter Cannabis Cultivars

The three basic types of cannabis plants are indica, sativa, and ruderalis. Each type of cannabis plant grows a little differently. Sativa strains grow the tallest and have the longest flowering time. Ruderalis grows the shortest and will flower regardless of the light schedule.

Autoflowering cannabis plants grow short naturally because they are part ruderalis. Most of the time they only grow to be 2 or 3 feet tall. They make great potted plants and will flower automatically regardless of the season and available sunlight. Autoflowers are a great choice for those growing outdoors in cooler climates.

Shorter light periods will trigger flowering in photoperiod plants like indicas and sativas. This switch will stop the plant from growing any taller as it focuses on bud growth.

There will be a short growth spurt when you switch to flower. Keep that in mind when growing under lights to keep a little extra space between the plants and the light.

Low Stress Training

If you simply tie down your branches as the plant grows, you can gently persuade the plant to grow out horizontally.
Once you’ve grown a few plants, you will begin to see the grow pattern of the plant.

Each node usually has 2 branches. The next node will have two more branches perpendicular to the first set. Tie down each one of these branches to help spread out the plant. You can read more information about training your cannabis plants here.

Main-lining is a grow method that is great if you have very limited vertical space. You first start by topping the plant fairly early and tying down the two new branches 180 degrees from each other forming a “T”. Using this method helps your plants grow more evenly, shorter, and helps support larger colas.

Light Problems (AKA stretchy cannabis plants)

There’s another reason why you might be here. Your plant is growing tall and stretchy with large spaces between the nodes (where the leaf meets the stem). Maybe your seedling is also growing very tall and falling under its own weight.
This is usually caused by not enough light or not the right kind of light indoors.
Blue spectrum light is the key to this phenomenon.  Perhaps the light you’re using is an incandescent bulb, it might not be giving off any blue light. If you’re starting plants off inside using a regular bulb use a “cool white” bulb. These shine white light with higher levels of blue. Check out our article about the light spectrum and cannabis for more information.

The cannabis plant is an amazing example of how plants will adapt to their environment to facilitate growth. Knowing how the plant grows will help you get a better idea of how tall your plant will be in 3 months. Having this knowledge and these techniques will help you grow shorter happier plants!

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