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What To Do When Your Cannabis Plants Grow Too Tall

Everybody loves big cannabis plants, but sometimes they can get too tall. This is bad news in a restricted space or for the stealth outdoor grower. Find out how to control your overeager marijuana plants with this informative blog from Royal Queen Seeds.

WHEN CANNABIS GROWS TOO TALL

When marijuana is exposed to prime growing conditions, it should fulfill its genetic potential. Sometimes, this means your plants will grow too tall. This can easily happen with sativas that stretch substantially or Kush varieties that tend to have generous distances between nodes. Some species of cannabis stretch notoriously when they enter the flowering phase, even doubling their vegetative height in some cases. Although the whole idea is to get the largest of plants with the heaviest yields of mature flowers possible, depending on the situation, plants that are too tall can be inconvenient.

Often, space is limited indoors and plants that are too tall can exceed the height of the grow space. If the grow room is a multi-strain grow, raising the lights to suit the taller plants can deprive shorter plants of sufficient lighting. Outdoors, especially in stealth grows, plants that are too tall can attract unwanted attention. Controlling the height of your marijuana plants is not very difficult and can be done in a number of ways. Here are a few techniques that can keep the height of your marijuana under control.

THINK AHEAD

If you are well aware that the strain you are growing is going to be tall, then height control starts in the early vegetative phase. Alternatively, the size of your grow space may require height control no matter the strain. Topping or fimming when plants are young encourages a shorter, but bushier plant. Grow room space still needs to be considered, however, as you are exchanging height for floor area.

Air circulation is a priority when plants become bushier in tight quarters. Controlling the height of your crop, only to suffer from mould or fungus due to lack of circulation is definitely a no-no. Lollipopping your plants will guarantee good air circulation below the canopy, preventing pathogens from taking hold. This also has the added bonus of chunkier and weightier colas come harvest, with less unwanted popcorn buds.

TRAINING

LST or low stress training is the art of gently tying the branches of your plants to grow more horizontally. Either the main stem is tied down, encouraging the side branches to be dominant, after which the side branches are also tied down; or the plants are topped a number of times and the new growth is tied down in the mainlining style. LST and mainlining have the benefit of exposing more of the plant to light, therefore encouraging weightier flowers all over.

What’s great about these techniques is an even canopy instead of one main cola. The extreme of this style is ScrOGging, in which the whole plant is encouraged to grow horizontally. A screen of netting is used to hold down all new growth until the plants form a mat. Appropriately called “screen of green,” one or two plants may fill an entire grow space.

PRE-FLOWER TOPPING

Letting your plants grow untouched during the vegetative phase, then topping just prior to flowering also controls height. When your plants are about to enter the flowering stage, top all branches. This has the effect of reining in the flower stretch. The plants are urged to produce new flower growth instead of focussing energy on stretching out.

Occasionally, pre-flower topping needs to be a full pre-flower pruning. If your plants fill the grow space during the vegetative phase, there is no way there will be enough room for flowering. It is time to get drastic. Aggressively prune the plants to half their size and switch lights to the 12/12 flower cycle. Don’t worry, cannabis is very hardy and can even recover from being reduced to a stalk with only one or two leaves remaining. Try not to beat yourself up about the loss of time and reduced final yields. All lessons are good lessons on the way to becoming a weed growing expert.

HUMIDITY

Cannabis plants transpire a substantial amount of water. Marijuana prefers a relative humidity (RH) of 50-65%. When they get too big, humidity can become a problem as the plants constantly release water vapor into the air. Water then gathers on leaves and other surfaces in the grow room, potentially causing mould and other issues. If humidity is becoming a problem, the use of a dehumidifier or increasing exhaust fan power can help. Defoliating can also increase airflow to control humidity. Remove lower and mid-level fan leaves only. This has the added benefit of increasing light penetration to the lower flowering branches.

TEMPERATURE

As with humidity, when plants get too big, temperature in the grow-op can rise. Reduced airflow and excessive height can drive up temperature and position plants too close to grow lights. Cannabis thrives when the temperature averages 25°C. When temps exceed this, plants are more likely to stretch. High temperatures can also affect leaf and flower formations, as well as final bud flavours and potency.

LIGHT INTENSITY

If your plants are getting too tall or too hot and you have the room, simply raise the grow lights as high as possible. Remember, lights that are too far from the tops of your plants can also cause stretching, so make sure to achieve the ideal light positioning.

Light intensity can be adjusted as a method for controlling growth speed and height. Some grow lights have adjustable outputs. If your plants are getting unruly, reduce the intensity. If you are using more than one lamp, simply turn some off.

During the flowering phase, growth can be controlled by reducing the photoperiod – but only if your plants have been flowering for at least six weeks. Reducing leaf production and stem stretching can be achieved by reducing the “lights-on” period from 12 hours to 11 or 10 hours.

CHOOSE WISELY

Appropriate strain choice can help avoid height issues before they even arise. If you have limited space, your dreams of cultivating a classic sativa will need to remain just that, dreams. Stout indicas and hybrids or autoflowering genetics can keep heights under control. Many autoflowering strains are ideal for indoor growing as they have relatively no vegetative period. Some strains will not grow taller than 50cm, but will still provide excellent yields per m².

DON’T WORRY, BE HAPPY

With a little bit of consideration and forethought, height need not be an issue when growing marijuana. Some research into strain characteristics is the first, very important step. Then, appropriate growing techniques will make sure you get lots of yummy buds with no drama. Happy growing!

Cannabis is a hardy plant that can grow too tall for your grow space if you just let it go. Sometimes you need to take charge to keep things under control.

How tall will my plant grow? And how long will it take?

Question: How tall should I expect my marijuana plants to get? And how long does it take until harvest?

How long will it take?

How tall will it grow?

Get the answers below!

These are very common questions for new growers, so let me give you the straight answers…

How long will my marijuana plant take to grow? How long from seed to harvest?

It will be 8 weeks – 6+ Months before your plants are ready to harvest.

But that’s a huge range, right?

The truth is, the time to harvest depends on your growing method, whether you grow inside or outside, your strain, and your desired yields…

Growing Method – soil tends to be the slowest growing medium, and hydro tends to create the fastest growth

Inside or Outside – In general, outdoor plants need longer to harvest than indoor plants. Outdoors, you plant in the spring, and harvest in late fall, taking 5-6 months or more. Indoors you have more control over the plant and can choose how long you want your plants to grow before harvest, and can get to harvest in just a few months. Indoors you can also start growing at any time (you don’t have to wait until Spring to start growing).

Strain – Some strains tend to have shorter lives, and others need longer before they’re ready to harvest. For example, you can choose to grow an auto-flowering strain to get to harvest in as short as 8 weeks. But many strains which originated near the equator can take months and months before their buds are ready to harvest, even when growing indoors. So strain is important when it comes to time-to-harvest.

Desired Yields – If you want bigger yields, you need a bigger plant, and that takes more time to grow than a small one.

Discover Exactly How Long It Takes Before You Get to Harvest

How tall will my marijuana plants get?

Plants can be grown shorter than your knees, or taller than your house.

Basically you (the grower) are in complete control of how tall your cannabis plants grow.

This is especially true for indoor growers, where you are in charge of nearly everything. When growing outdoors, you still have a bit of control over plant height, but you are also at the mercy of the sun and the elements.

Some strains tend to grow tall and thin, while others tend to grow short and squat, but you can force your plant to grow differently when growing cannabis indoors. In fact, you have many options to control the exact shape and size of your plant.

To learn about all the tools and techniques you have available to control the height and shape of your plant, take a look at our Plant Training & Height Control guide!

Short plant in a small space – this plant is only about two feet tall thanks to training with a screen, yet still producing lots of bud! You don’t need a huge space to get a good harvest when you use plant training.

These cannabis plants were also trained to stay short, this time using LST – they were under two feet tall at harvest and produced more than 6 ounces of bud under a small grow light!

These plants were trained using manifolding. They were about 5 feet tall at harvest, and produced more than a pound of bud!

You can achieve almost any size or shape when growing indoors as long as you use plant training. But if a cannabis plant is left to grow outside with tons of sun and without any plant training, the sky is the limit for how big they can get!

Although it isn’t the be-all end-all when it comes to size, strain is still definitely something to keep in mind when it comes to height. Although you can control the exact height and shape of your plant no matter what the strain with plant training, different strains grow differently and you want a strain that makes it easier to get the results you want. When growing with bagseed (seeds that you find in your buds) you often don’t know what to expect until the plant actually starts growing.

For example, some strains (known as “indica” strains tend to stay short, while “sativa” strains tend to grow tall). Just to give you an idea of the difference, these plants were grown in the exact same setup.

To fight these natural tendencies and force these plants to be the same height, the grower would have needed to use different techniques and training strategies. If the grower had wanted to make the right plant shorter, the plant would have needed more Low Stress Training and Supercropping.

For the left plant to grow taller, the grower would have needed to give the plant more time, since indicas tend to stay short. So even though you can force plants to grow into any size and shape, it’s often easier to start with a strain that naturally grows the way you want. That way your plant is working with you instead of against you. Learn how to find the right strain for your needs.

Learn more about how to get your plants to grow the size and height you want!

FOR SERIOUS GROWERS ONLY

You’ve told me you’re looking for a complete guide to growing marijuana that covers everything, from beginner to ultra-advanced.

And super cropping is just one technique to getting seriously killer harvests. If you want to learn ALL the secrets…

Learn from the best!

Total care explained step-by-step… indoors… outdoors…

Monster cropping… advanced growth control… bud production secrets… and much, much more…

Over 700 pages of pictures, tutorials and advanced insider tips!

Get Instant Access to It All Right Here: GrowWeedEasy.com/growing-elite-marijuana

I thought I already knew it all, but after I went through this grow bible, I discovered that there were still lots of easy ways I could increase my yields and grow even more potent buds! I find myself going back to it again and again for new ideas.

About Nebula Haze

In response to the need for more tutorials aimed at new growers, Nebula co-founded GrowWeedEasy.com in 2010 with fellow grower Sirius Fourside.

Since then, Nebula has published hundreds of growing articles in print and online, and continues to dedicate herself to serving the medical marijuana growing community.

“My mission is to show other medical marijuana patients how easy it can be to grow weed out of your closet.”

[Answer inside!] These are very common questions for new growers, so let me give you the straight answers…