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How To Deal With Stretching Marijuana Plants

How To Deal With Stretching Marijuana Plants

When you have marijuana plants with stretching stems, this can be an issue both indoors and outdoors.

There are several reasons why marijuana plants may stretch. Apparently, genetics play is a major role in this. Sometimes there is nothing you can do and the plant will create tall stems regardless of your efforts to stop it. One example of a strain that grows tall both indoors and outdoors is tropical and land race pure Sativa. However, you do have options for ways to reduce stem height between the leaves.

Why is stem stretching an issue

Why is stem stretching an issue

When growing indoors, stretching may seriously lessen your yields because of the challenges with imitation lighting. This may also create very weak stems, which means the plant is at risk of falling over. It is also definitely an issue where ceiling height is a concern.

Ways to reduce stretching

Ways to reduce cannabis seedling stretching

Air Circulation
Having good air circulation will allow the stems and leaves to get thicker and stronger while at the same time reducing how high it grows.

Strong air circulation can create stem and leaf movement that strengthens and widens the stem while also slowing its vertical growth. Winds will bend the stem, creating small rips in the plant’s tissue. You can also just brush the leaves to simulate the effects of air circulation.

Light Spectrum
The type of light you use also plays a role in how tall your stems will grow. Orange and red lights provoke taller, thin stems, but thick, short stems blue light is best. Using metal halide lamps while the plant is in the vegetative stage will produce short stems.

Another way to control the height of your plant is by using infrared light. You use these when the lights are off. There is a black cloth that covers the heat lamp reflector, which makes it so the infrared rays create the right results. At the same time, it catches red light to prevent contradicting what you are trying to accomplish. It is best to only use this light during the flowering stage.

Heat and Stem Growth
The temperature influences how your stems grow. The higher the temperature, the longer the stems will grow. Your plant’s stems will widen and the growth will lessen at about 60*F. When you have it around 80*F, the stems and buds will begin stretching.

If your buds get too close to the light, this causes it to become tall and thin. Don’t make the mistake of thinking this is light burn because this is not the case. In fact, the heat from the lamps can make it unbearable for buds. Air-cooled lamps are great for keeping much of the heat from coming into the room.

Not having the proper amount of light will lead to stem stretching. As a result, the seedlings will grow tall, thin stems because it is trying to access more light. As a solution to this problem, give it a more intense light schedule or you can place them nearer to the light. Once you have done this, the stems will grow thicker and do much better on their own.

Lastly, try pruning as a way to reduce stem stretching. By cutting off the top of the stem, it makes the rest of the branch grow.

Spacing In-between Plants
Growing your plants in bulk leads stretching. As your plant grows, the leaves may easily start coinciding with the plant next to it. Over time, this causes the bottom of the plant to be discolored and the sub-canopy will get darker.

Reduce Stress
Stem stretching is the result of many factors, which include high/low temperatures, transplant shock, light spectrums and humidity. Keep your plant happy by making sure the environment is the best for your plant.

Tips for stem stretching

Tips for  cannabis seedling stem stretching

There are times when some growers like a bit of stretch since this is good for avoiding bud rot in certain strains. But in most cases stem stretching is not desirable.

During the vegetative state and the first two weeks of the flowering stage use blue lights to reduce stretching. If your plant is stretching, refrain from giving it too much nitrogen. Instead use a fertilizer ratio of (2-2-2) at the beginning of the flowering stage to keep the nitrogen levels average. Making an instant shift to the normal flowering ration right after the vegetative stage causes yellowing. Lastly, remember to use oscillating fans to help make your stems healthier.

Remember that plants with strong genetics have less change of getting sick and are less vulnerable for diseases, deficiency’s, pest and environmental stresses. So make sure to buy marijuana seeds from a trusted seed bank.

Thanks for reading. Please leave comments or questions below and don’t forget to download my free grow bible


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Comment Section

32 thoughts on “How To Deal With Stretching Marijuana Plants

By Jon on 24 July 2014

What is the difference between indoor and out door seeds? Does it really matter one way or the other?

By Budzila on 3 January 2016

BUDZILA here when is it a good time to start germination my seeds and the best-known way to due so please.

By David 1954 on 5 June 2015

Hi, Great reading well explained. Thanks.

By Aniya on 11 June 2015


By pat on 30 December 2015

Can you say the reasions y one plant turnes male and the rest are fine this is at the start and the serds are femanised regards pat

By Brian on 30 December 2015

I usually use a single t5 grow light for my seedlings until they get about 5 or 6 inches tall. Is this OK? I bought a 4′ 4 light t5 also for when they grow bigger then switch to a 400 watt HPS. How does this sound to you? Thanks

By Stephan on 30 December 2015

I would like to get ur bible book , not a email! I don’t know if it’s possible? If it is
154E County Rd 14

And I thanks u for all the help u gave me so far!!!

By Jennifer ILGM on 3 January 2016

Hi Stephan, Unfortunately the Bible is only available in as an e-book and not in hard copy.

By BrianK on 10 January 2016

just print it out and put in a binder, that might help =)

By ruven golan on 30 December 2015

Please anyone have recommendations for supporting weak elongated stems?
Is supporting by elevating the soil around the stem OK?

By Jean on 31 December 2015

@Ruven, probably not. You can do that for things like tomato seedlings, because all of those little “hairs” on the stem can turn into roots if they’re covered with soil. I don’t know that cannabis has that ability, and so you might be inviting rot.

Would probably be better to run some fabric strips or soft yarn from one side to the other, supporting the seedlings between them. Like a sort of lattice. If you’re using a greenhouse type structure, you could tie it to the poles on either side. Otherwise, you could “stake it” in the soil around the plant. Make sure not to let it cut into the plant. You want it to provide support, that’s all.

By Richard on 31 December 2015

Tomatoes do produce adventitious roots almost anywhere along the stem. They aren’t associated with the “hairs” you can see but the bumps that form from the base up the stem. In fact, when I transplant tomatoes, I lay the plant on its side in a trench turning up the growing tip. The root system then develops along the buried stem.

To my knowledge, cannabis does not have that capacity. Robert has promised an article on cloning (I haven’t found it using the search engine associated with his site). I’m sure the process will be similar to rooting common garden plants with woody stems.


By Bob Smith on 28 February 2016

Say there Ruven:
I use bamboo stakes and narrow green tape and tie them loosely. The tape is available in most grow stores.
Also there is a product called “Silca” Several companies make this and it works to build stronger stems. I also use Amino acids and that is helpful.

By Art on 17 May 2016

Tie to 3,4 or 5′ stakes. Bought at any grow shop. If you need shorter stakes cut to size

By Jean on 31 December 2015

“Not having the proper amount of light will lead to stem stretching. As a result, the seedlings will grow tall, thin stems because it is trying to access more light. As a solution to this problem, give it a more intense light schedule or you can place them nearer to the light. Once you have done this, the stems will grow thicker and do much better on their own.”

^^ This is the most common thing when it comes to stretching of any seedling, not just cannabis. People all too often don’t realize they need to put the lights pretty close to the seedlings, like, within a couple inches, and from the very beginning of the process. Otherwise, they will stretch quickly, and you can’t really reverse that.

By Lucinda on 31 December 2015

I treat mine like tomatoes and if they stretch I bury them deeper just like a tomato plant, but only in the seedling stage. Mine always do well and have more roots because I plant them deeper to cover the stem.

By Richard on 31 December 2015


A quibble and a question about light:

There have been two changes in the way artificial light is designated. Lumens has replace watts as we’ve moved away from incandescent lamps. And with the advent of tuned LED’s “degrees Kelvin” has replaced the familiar white, warm white, blue, etc.

The question concerns the description of light color. Could you, even if parenthetically, define your color recommendations in degrees K? As for LED’s: as they become more reliable and cheaper, and since they can be precisely tuned during manufacture, is there a reason not to use these bright yet relatively cool running lights?

By latewood.ILGM on 4 January 2016


We still measure lighting in watts and lumens. What has happened is that the LED industry is so Non-Standardized, that it actually takes buying and experimenting with the different brands in order to realize at what values they function. I use HID digital lamps, and T5 for propagation. LED is still too expensive and has too many misleading ratings for me to invest at this point.

Best advice I can give you is to join our Support forum and open a discussion with some members and experts who use LED lighting.

Peace, lw

By darryl on 5 January 2016

to growers, i used led 200 watt for seedlings, but my light is about half way of my tent due to plant stretching and it works for me, once i start on my forth nod i throw them into a bigger tent with less mix color also i run them about half way of my tent. i guess is that how tall and how wide your tent may be, take that into consideration that it also plays a part into stretching of your plant. at one time i started my seeds and threw them into my big tent with mix leds it didn’t produce anything for my seedling also so i have put them into my germ tent and it started to grow so i guess light plays a important thing when your germ and plant stretch

By Itsme on 29 September 2016

Side by side plants in 5L pots using the same soil and sharing a 1.5m LED grow strip light. One plant shot up and the other stayed short and bushed out?? Had to raise one end of the strip light just about every day to accommodate the tall plant. After 45 degrees I gave up and put the tall plant outside. Kinda late in the season as the days are getting shorter. The two outside plants are budding like crazy and I’m hoping the tall one will start. Next spring I’m going to plant all of them outside. This group was just an experiment.

By Eric Bowers on 30 September 2016

The solutions only cover indoor grows. When growing outdoors, someone want to explai how to get it closer to the light? Lol. But would be great info if I was growing indoors.

By latewood.ILGM on 3 October 2016

Put it on a Large pedestal!? LOLI guess it is too bad you are not growing indoors, LOL.

By Darren Kirk on 4 December 2016

Ive just stated to grow,and ive got 2little seedlings,I only have a 400w bulb so I have been putting it on for 2hours a time to heat my little cupboard then I put it off.I do this 3times a day and they have grown to about 2″-3″ stocks with 4little leaves,im worried if the stocks r too big or if I should plant them into a bigger pot,sorry I should have said that I used riot root cubes thats all they r in at moment can anyone advise me

By latewood.ILGM on 5 December 2016

Darren Kirk,

I do not understand why you are only running light 2 houes…

Light should be on 14-18 hrs per day, and off the rest.

Stretching is due to plants reaching for light. Best way to prevent stretching is to invest in a T5 lamp with at least 4 bulbs. You place a T5 1″ above seedlings, and they do not stretch. Your stretching appears to be due to”no light’ at all.

I advise you to join our support forum where you can learn from our many helpful and friendly members, and experts alike.

Happy growing! 🙂

By j cameron on 14 January 2017

best compost for growing plants indoors

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