Why are my marijuana plant stems purple?

Seeing your marijuana plant with purple stems can be a little scary. You may become quite worried about the overall health of your plant, but this may not be as bad as you think. Below are some things you need to know about cannabis purple stems.

Purple marijuana stems

Let’s say you are growing your plants indoors, the plants are still fairly young and the leave are average in size, but you notice the stems have turned a purple color starting from the top.

purple weed stem
Purple stem

If you notice the stem of your seedling or marijuana plant has turned purple and there are no more indications of issues, this means their problem is genetic.

There are certain marijuana strains that automatically grow with purple stems, more so when the seedlings are budding, or even once the plants start receiving cooler temperatures during the night.

Solution for purple stems

If your plant seems to be in good condition aside from the stems being purple, refrain from making any changes for a one or two weeks. The majority of the time the plants will turn green fairly quickly. Provided that your leaves appear to be healthy and there aren’t any of issues you are aware of, most likely the purple stems are nothing to be concerned about.

If your marijuana plant is struggling to grow properly you might want to check out our list of nutrient deficiencies to get ahead of the issue!

If you suspect that your marijuana plant may have a nutrient deficiency, maybe because the plant growth has slowed down or the color of the leaves is fading, then your plant could be magnesium deficient. This can sometimes create purples stems.

purple stems cannabis
Plant with all stems purple

If this is the case, the issue will be resolved with ease by adding more magnesium the next time you water your marijuana plant.

Here are some great magnesium sources for your plants:

  • Epsom salt, just add 1 tablespoon per gallon
  • Cal-Mag
  • A nutrient solution that works well with marijuana has the proper amount of magnesium for your plants

Make sure to download my free Grow Bible for more information about purple stems cannabis.

Usually, your purple stem problem is nothing to worry about at all. But to be on the safe side check for any signs of magnesium deficiency. Take a look at our article on identifying magnesium deficiency for more detailed information. If there is no nutrient deficiency, then luckily, purple stem will only last for a short time.

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


FAQ cannabis purple stems

What causes purple stems

If you notice the stem of your seedling or marijuana plant has turned purple and there are no more indications of issues, this means their problem is genetic.

How do you treat purple stems

If you suspect that your marijuana plant may have a nutrient deficiency. If this is the case, the issue will be resolved with ease by adding more magnesium the next time you water your marijuana plant.

How do you fix weak stems?

If it’s stretching, add more soil right up to the first set of leaves to strengthen the stem.

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Robert Bergman


Robert Bergman is an Amsterdam-based marijuana grow expert who has years of experience from small grows to massive operations ... See profile

39 comments on “Why are my marijuana plant stems purple?”

  1. my leaves are purple but my stems are green. I don’t know if this is due to a lack of phosphorus or if it is the strain. if it is a lack of phosphorus, will this affect the bud

  2. I have 3 gorilla glue clones , one entire plant has all purple stems. The only one , they all get the same feeding.. Very healthy looking plant.

  3. Purple stem yes ,the banana looking object growing on the stem , should I be concerned , male , or hermafidite ,.

  4. Thank you for the information my outside plants my stem was getting purple from the bottom of the stem looks like from cold temperatures at night Thank you once again

  5. Appreciate the information. 🙂 I was a little worried that my seedlings that just popped out of the soil might already be having some issues. Thank you

  6. It’s not about this article…but I had bug problem…”outside” so what I did was. Lightly Sprinkle some black pepper around the base of the plants and lightly over the leaves…it worked no more bug problem..

  7. Thanks really helps me allot Im think im need callmag but im not ben sure now im know for sure hehe thsnks again

  8. Everyone says that some strains have purple strpems….but no one lists which strains….. It would be advantageous to provide this information.

    • Karen.

      This is a deficiency article. Please join us at: support.ilovegrowingmarijuana.com where we are set up to help you in a Q and A format which allows you to post pictures. Foam build up in your reservoir is caused by something you added to solution.

      See you at the support forum

      Happy growing 🙂

  9. Wonder,

    Thanks for catching that. I will send the edit info to the editor. Again. What was mentioned that I agree with is: The cause of purple in most cases is genetic. Happy growing 🙂

  10. every grower of cannibus has there different ways of growing great nugs the biggest thsia seed at this time and a little more intense just be patienting is dont ignore your medicine and alot of patience just dont be in a hurry i am on my eighted grow right now indoor grows under 1000 watt metal halide from seed to harvest i am growing a amne

    • Skip. Go here: support.ilovegrowingmarijuana.com

      We have a super friendly community. Experienced growers and expert staff will to help you grow successfully from start to finish.

      It sounds like you placed a seed into hot fertilized soil. Nutrients burn the roots of a young plant. It shrivels and dies. Otherwise; It was due to total lack of water. Hoin the forum. See you there. 🙂

    • Shaun,

      No. It is not normal to leave the lights on for 24 hours. Plants need rest, just like humans. 😉

      Purple stems. Could be too cold an environment or a deficiency. Perhaps you should join our support forum. We have many helpful graphs and images to help you diagnose your issues. Just ask! 🙂

  11. Hi (already a pun). I am growing several types of Pot from seed, including the 3 precious seeds i got from my ‘Purple Kush’, …all from a medical dispensary. There are 3 of 14 plants exhibiting the purple branches, one, a purple stem, all are in excellent health, potted, and outdoors..we have had cooler than normal temperatures. They are good size, but not large enough to sex, other than to guess, based on their structural morphology. I also DO Use ~ 30% natural, earthworm rich topsoil, mixed with organic compost and premium potting soil. Much to the dismay of others, who begin their seedlings in what i consider much too small a pot (considering these tiny seedling are fed dilute mineral gro)…my plants are extremely happy outside, healthy – and carefully tended, produce outstanding (proper cure ESSENTIAL-no cheating on time!) lasting mellowness, what aches?

  12. I live in COLORADO most of my STRAINS have the the PURPLE STEMS
    I believe its GENETICS .I have 4 indoor and 4 outdoor .I use ROOTS707 soil
    NUTREINTS . MY LEAFS are SUPER GREEN and ONLY FAN LEAF STEM TURN COLOR. The BUD is ALWAYS GOOD AT HARVEST. I Take clones from plants before I flower. So I have a steady supply.

  13. King Spike,

    Sounds like you have a plan; However, Using common dirt from the ground can lead to unwanted pests and possibly could be detrimental to your plant.

    I advise you to join our support forum. We have many knowledgeable members and experts always willing to help. 🙂

    Happy Growing, lw

  14. Hello, first time grower here. My plants are just 2 decent mid grade seeds I got from a friend. The plants are about a month old. I transplanted them into bigger containers with a mix of 10-10-10, good garden dirt and a layer of top soil. These are just outdoor plants right now. Any advice?

  15. Mark,

    Purple pot 🙂 I think it is more important to yield quality pot before worrying about color. 🙂

    Most off colored buds comes from colder temps in flower. I always appreciated what nature provided me, concentrating on a fine finished product over looks or color of same.

    That’s all I got, today 😉

    Happy growing

  16. Purple pot is one thing. How about other colours I have seen over the years. I have been growing many years. Kind regards, Mark.

  17. Sounds like you lost that one, mate. Start again. Download and read Robert’s Free grow bible and learn how to start seeds correctly and keep them thriving.

  18. My plant is wilted an it was doing great till I switched it from 1 bucket to another b cuz it’s to big red my arogarden an I need to knw if it’s gonna make it an will it harm my plant if I move it daily from light an then transplanting

  19. Thanks for that info about the purple stems which look exactly like the stems in the photo on your page.
    My plants are only 4 weeks old and Auto flowering, the nutrients I am using do contain Mg so it is most probably genetic as you suggest. The leaves look healthy otherwise and are growing well. under lights in the grow tent.

    I intend to sterilize the tent between grows to prevent the possibility of any cross infection and top kill any mold which may form I don’t know whether this is recommended practice but hygiene is usually a good thing.

    • Accidentally left my Greenhouse closed for 5 hours during a hot morning….the top 20% of plants are burnt and brown…not sure what to do…they were beautiful ..7 ft tall full..now burnt all over the tops…what should I do.