For outdoor growers, cultivating gigantic tree-sized plants is pretty normal. But for indoor growers, tall marijuana plants can spell disaster. If a plant grows too high, it can literally reach an indoor garden’s light source and start suffering from light burns. Once that happens, there’s not much you can do – get ready for scorched leaves, branches, flowers, and overall ruined harvest.
As always with cannabis, an ounce of prevention is worth a pound of cure. In this post, we’ll explore how to keep marijuana plants short when cultivating an indoor garden.
Why Are My Cannabis Plants Growing Too Tall?
There are a few reasons your garden may be sprouting tall cannabis plants. Some strains, including all sativas and Kush-dominant indicas, just like to grow tall and lanky. If you have sativa pot plants growing tall and skinny, chances are they’re healthy and your growing space is just too small.
In addition, you may have let your plants veg out for too long. Long veg cycles definitely offer plenty of advantages. However, if you’re an indoor grower, your garden may not actually have enough space to grow tall cannabis plants. As a result, long veg cycles can seriously threaten your garden.
Finally, environmental factors can play a part in a cannabis plants’ growth. If you don’t give your plants enough light, they’ll begin stretching to “find the sun.” The same is true for temperature and humidity levels. If your garden is too hot and humid, your plants will begin stretching to try and escape. Luckily, there are a few ways you can avoid this outcome.
How to Keep Marijuana Plants Short
Wondering how to keep weed plants short? You could shorten your veg cycle, apply a few different training methods, or dial in your light or environmental factors. We’ll cover how to do those things below.
Don’t Extend Veg Cycle
The easiest way to avoid weed overgrowth is to keep your veg cycle short. It definitely can be tempting to veg your plants out for a while. After all, the longer you veg a plant, the higher its yield will be. However, this isn’t always the right strategy when growing indoors.
The longer you veg your plant, the taller it will grow. If growing indoors with limited vertical space, limit your veg cycle. After your plant germinates and takes root in its cube, transplant it. Then, only give it a minimum of two weeks to establish its root system before flipping into flower. Remember that cannabis, especially the sativa type, tends to keep stretching even after the flip - take this into account.
Training Methods
Several training methods can help control weed overgrowth. They include:
- Topping – this technique involves removing the top node of a plant in the veg phase. See our full guide to topping for more info.
- LST or HST – both techniques can help manage vertical space in a garden. We’ve outlined the details here.
- ScrOG – another effective way to grow wide instead of tall. Learn more here.
Light Levels
Low light levels can lead to pot plants growing tall and skinny. This isn’t exclusive to weed plants. In fact, you can see succulents demonstrating this same behavior if they’re not getting enough sun.
There are several ways you can fix this. First, some grow lamps have adjustable outputs. If you’re fortunate enough to have one of these lamps, simply crank up your output wattage. If not, you can physically lower your light to reduce the distance between it and your plant. You may have to adjust your lamp’s height as your plant grows, but this will help manage your plant’s vertical stretch.
What to Do with Tall Marijuana Plants
Ok, so you did everything right to manage your marijuana plant height. You tried to train your plants to stay low and increased light levels. But your plants are still shooting up towards your lights. What can you do?!
If you find yourself in the middle of a flower cycle and need to shorter your plants, don’t worry. You have options – namely, supercropping.
Supercropping is a training technique that involves twisting a plant’s branches gently until they emit an audible “pop.” The branches will then bend at the twist point. Use this technique to knock back any high branches from particularly tall cannabis plants. If you use supercropping, make sure to give the branch some extra support. Insert a metal garden stake into your soil and attach the branch to it some green gardening wire.
You shouldn’t plan on supercropping in this way when you start a grow cycle. But in a pinch, it can help save runaway branches.
Finally, controlling temperature and humidity can help prevent some problems associated with tall cannabis plants. Remember that plants give off more heat and humidity as they get bigger. As a result, you may need to adjust temperature and humidity throughout the growing cycle.
Remember: a cannabis plant’s favorite temperature is 77oF (25oC). If the temperature in your garden begins to substantially exceed this, you’ll need to introduce air conditioning. The same is true of humidity. Cannabis plants like between 50 and 65 percent relative humidity (this number can decrease further into the flower cycle). Tall cannabis plants can result if your humidity spikes above this.
Best Strains for Managing Marijuana Plant Height
Here’s one last tip for managing weed overgrowth. Use the right genetics! Some strains, like autoflowering and indica genetics, grow short and bushy. That makes them perfect for indoor growers. Need some suggestions? We’ve included a few of our favorite choices here.
Girl Scout Cookies Auto
Girl Scout Cookies Auto (Cookies Auto) (Fast Buds) - Autoflowering
- A portion of vivacity and good mood
- 20 %
- 450 - 600 g/m² indoors
50 - 250 g/plant outdoors
What, you thought we’d have a list of indicas and autoflowers that didn’t include Girl Scout Cookies? This version of the legendary Girl Scout Cookies checks both the indica and autoflower boxes. This variant offers several advantages to those wondering how to keep weed plants short.
For one, it maxes out at 3.3 feet (100 cm) in height. Since it’s an autoflower strain, it’ll automatically flip from the veg into the flower cycle. As a result, you won’t need to worry about over vegging. Add in its sweet flavor and 22% THC level, and you’ve got a winning strain.
Blackberry Gum Auto
With a sweet taste that combines blueberry and bubble gum, this strain helps gardeners avoid tall cannabis plants. Blackberry Gum Auto boasts both a 22% THC concentration and ruderalis-centered genetics. As a result, not only does it reduce a grower’s necessary vertical space, but it doesn’t compromise quality. For cotton candy flavor and easy-to-manage autoflower genetics, this strain excels.
Shishkaberry
Our last entry in this guide to limiting weed overgrowth is Shishkaberry. This Blueberry x Afghan manages to combine a short photoperiod and fast-growing genetics. With a growing period that maxes out at 56 days and a max height of almost 4 feet (120 centimeters) this indica-dominant heavy-hitter doesn’t mess around. And with 26% THC content, this strain is sure to satisfy even the connoisseurs.
Final Thoughts on Uncontrollable Marijuana Plant Height
If you’re trying to keep your marijuana plant height under control, you have several options available. Remember, while your plants may be healthy and growing tall, you still need to manage their height in your garden. Good luck!
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