How to regenerate cannabis plants

Cannabis is an annual plant—wild plants germinate, grow, flower and die within the course of one year, in response to seasonal variations in daylight; the next year, new plants grow from seeds produced by the previous generation. However, it is possible to rejuvenate a plant after flowering, and ‘trick’ it into producing again.

How to do it

When harvesting a mature cannabis plant, the uppermost 1/3 of the plant, comprising all leaves, flowers and stems, should be removed entirely. The middle 1/3 should be selectively trimmed to remove the colas while leaving the majority of the larger fan leaves in place.

From the lowermost 1/3, the larger terminal flowers should be removed, but all smaller buds and all leaves should remain untouched. Many of these smaller buds are inconsequential in terms of dry weight, but are crucial in stimulating the regeneration process; thus, it is advisable to leave as many small buds on the lower branches as possible. Contrary to the cannabis plant’s normal growth pattern, during the process of regeneration new growth occurs more rapidly at the lower branches.

The concept behind it

How to regenerate cannabis plants
If a mature cannabis plant is trimmed until most of the buds and branches have been removed, it can be put back into vegetative growth mode and produce a second harvest

Once a plant has flowered, it must return to a short period of vegetative growth. This allows the plant to regrow more branches and leaves in preparation for a new round of flowering. In order to revert to vegetative growth, growers typically switch the lighting from a 12/12 back to an 18/6 (up to 24/0) schedule, while simultaneously switching the nutrient regime back to vegetative feeds.

A large dose of nitrogen is usually administered immediately after harvesting, to send a clear signal to the plant to recommence vegetative growth. An important point to remember is that as much of the plant is now missing, its water requirements will not be as high as immediately prior to harvest, and should be reduced to around two-thirds of that amount. After two weeks of vegetative growth, new growth should be well-established and the plant should be ready to revert to its next round of flowering.

There are several steps that can be undertaken to enhance the rejuvenation process beyond switching the lighting and nutrient regime. If growing in pots using soil, transplanting the plants to larger pots and replenishing most of the soil will encourage new root growth and vigorous vegetative growth.

Advantages of the technique

The most readily apparent advantage of regenerating cannabis plants is the time saved. As the root and stalk system is fully formed and some branches are retained, much of the time spent on vegetative growth can be avoided for subsequent flowering rounds. Thus, as just two weeks vegetative growth is sufficient to rejuvenate the plant, a second harvest can usually be completed in as little as eight weeks.

Another reason to rejuvenate a plant is to preserve genetics. If growing from seed, it is not always possible or convenient to take clones of every single specimen. Furthermore, when the plant flowers, far more can be learned of its characteristics and potential value than in the early vegetative period. Hence, it makes a great deal of sense to rejuvenate plants post-flowering, as not only can the plant itself be coaxed into producing more bud, but clones can then be taken during the two weeks of vegetative growth prior to the second round of flowering. It is also possible to keep the plant in vegetative growth indefinitely and continue to take clones.

It may even be possible to achieve increasing potency and flavour with successive harvests if certain steps are applied. According to some reports, pollinating the plant during alternating flower periods is the key to this increase in quality—for the initial flowering period, the plant should remain unpollinated, but during the next flower period after the plant has been reverted back to vegetative growth, the flowers should be exposed to male pollen. After a few cycles, the plant should achieve great size and produce excellent clones and flower. However, this technique is not widely known, and it is not clear how this process occurs, if indeed it even does.

Potential disadvantages

The biggest disadvantage of regenerating plants subsequent to flowering is that each successive harvest will yield less overall. It is also reported that there can be a reduction in quality with each harvest, although some argue that this is due to improper techniques (for example, nutrient build-up in hydro systems accumulating over time).

Regenerated plants are also subject to intense amounts of stress that can take several weeks for the plant to fully recover from. Often, signs of stress such as reduction in number of leaflets per leaf, shrivelled leaves, and generally slow growth can occur.

Clearly, regenerating plants is not suitable for everyone. In hydro systems, there are more potential disadvantages, and vegetative growth from clones occurs so quickly in hydro systems as to render any potential time savings all but negligible.

Regenerating outdoor plants

How to regenerate cannabis plants

Although regenerating cannabis is far easier indoor, where precise control of lighting and other environmental variables is possible, it is also possible to regenerate outdoor cannabis plants. This is usually only possible in regions with long growing seasons, or little seasonal temperature and photoperiod variation. For example, in subtropical regions such as Hawaii, there are reports of growers maintaining plants for several years, and producing multiple harvests.

How to regenerate cannabis plants

Basically, the key to successful outdoor rejuvenation is long day length. If it is possible to harvest your plants in June (in the northern hemisphere), then there will be sufficient time to allow the plants to re-vegetate for several weeks before the light level drops enough for flowering to recommence naturally. As with indoor plants, the upper 1/3 should be fully removed, the middle 1/3 should be selectively trimmed and the lower 1/3 should be left mainly intact save for larger colas. Make sure the plant receives plenty of nitrogen and sun, and the plant should resume vegetative growth within two weeks or so.

Regenerating autoflowering plants

Although reports of successful regeneration of autoflowering plants do exist, there is significant controversy and confusion surrounding the subject. Many people have successfully removed central colas from autoflowering plants, leaving the smaller buds behind, and have subsequently witnessed growth of new flowers.

However, the plants have not been demonstrated to revert back into the vegetative state, which is a crucial part of the regeneration process. Furthermore, most reports acknowledge that the new growth is slower and lower-yielding, and that the process is probably less effective than simply growing new plants from scratch.

Overall, it appears that regeneration of plants can have benefits in certain situations, for example when seeking to preserve genetics that were not cloned during the initial vegetative period; however, for many typical growers, the effort and complexity of successfully regenerating plants renders the process unfeasible.

  • Disclaimer:
    Laws and regulations regarding cannabis cultivation differ from country to country. Sensi Seeds therefore strongly advises you to check your local laws and regulations. Do not act in conflict with the law.

Comments

29 thoughts on “How to regenerate cannabis plants”

  1. Cannabis N.I.

    SWIM done this years ago with their first ever plant, Skunk 1. SWIM regenerated the plant and used it as a mother plant, Big Mama, she gave so much life :-). Unfortunatley the police took her away, and murdered her.

    You could use the gas lantern routine to regenerate, fool them into thinking it’s still summer.

    Has anyone at Seni ever tried grafting one strain onto another?

  2. Ryan McIlvenna

    I have been growing cannabis for close to fifteen years. During that time, I traveled throughout most of the western world collecting knowledge and genetics. While in Jamaica, I came across some of the best homegrown I ever smoked. The Rasta whom I spoke with explained his technique of regenerating his strains and how the potency of the plant would increase with each successive regeneration up until, the seventh generation and then on the eighth generation, there seemed to be little to no buzz. I am currently in my third rejuvenation cycle and the second flowering produced higher quality cannabis than the first round. I used the exact techniques as mentioned in this article to rejuvenate and have been successful each time. I will keep you posted.

    1. newbie 3737

      like your information mess around and left small buds on top of plant and forgot an left lights on new leaves started to grow out at the top of the plant will plant take off from the new growth. might have a ten foot plant bald till the top HELP>By the way shes supposed to be blueberry kush.

    2. So far it looks really good, to travail as far as you did, and bring back that info back to all the grower. I’m trying my luck with the DEA, all the way down to 501, to make it happen strong!! I would be very happy to talk to you!!??

    3. Ryan McIlvenna

      Kind Sir, I am attempting a regeneration on a auto flower. I am wondering in your regenerations do you use any type of sweeteners while feeding? I used a mix of molasses and mineral water to plants; It seemed to cause additional growth. Do you think it would help the 2nd one?

  3. Doing it too atm. Have been regenerating off and on over years and always have (usually ;-)) had good results. Just lately have had odd things with them, hence looking on places like here for others doing the same. Bit real world experience and sharing knowledge.
    Had great success putting indoor girls outside after harvesting and had one or two monsters grow on occasion.

  4. I am currently witnessing the regeneration (entering the flowering stage now) of an Auto Berry (f). I had no intention of experimenting with this process, but when I harvested this plant – I cut away all of the leaves and buds, except for a tiny leaf or two at the very base – I didn’t toss the soil under my peach tree as I usually do. I was busy and just put the pot for safety’s sake, back in the grow tent – not directly under any light. It started re-growing immediately, so I added more soil and started watering with nutrients. It went crazy and started showing flowers 3 weeks later.

    I have to add that this Auto Berry plant took 15 days longer to “finish” than any others I’ve grown, so I’m wondering if its genetics are more Blueberry or Grapefruit than Ruderalis and that is why the regeneration occured.

    As I say about most things unfamiliar to me, “It’s all in the name of science!

  5. Just wondering….when they say add nitrogen to my plant….exactly what do they mean?? Pretty sure you can tell I’m new to this.

    1. Scarlet Palmer - Sensi Seeds

      Hi Newbie

      Thanks for your comment. For basic troubleshooting, this is a good post: What’s wrong with my cannabis plant? . We can’t really answer questions to do with growing on the blog, which is why we have the Sensi Seeds Forum; you can browse topics and ask questions to your heart’s content 🙂 This thread has some useful info about nitrogen, do read the first few posts as it depends what medium you are growing in as to what the best way to add nitrogen is. Good luck and happy growing!

      With best wishes,

      Scarlet

  6. I harvested three plants about a month ago. I chopped them just above the last nodes at the bottom. One died. The second one went brown from the top down about an inch but green the rest. It’s has one small shoot coming out about half way down. The third has some growth that I had left on the top but no new growth. They were indoor but now they are outdoor because we are getting long days right now.

    Any ideas on how to jump start them back into veg?

    Pictures are here:

    https://www.dropbox.com/sc/82kay60s4pc3g2e/AABi9kUp5-fGi_A5e5Izrzwma

    1. Scarlet Palmer - Sensi Seeds

      Hello Wallstud,

      Thank you for your comment ? Unfortunately we cannot respond to grow questions on the blog, but we do have the Sensi Seeds Forum where you can ask a thriving community of gardening fans for advice, share your experiences, and see if your question has already been covered. I hope this helps.

      With best wishes

      Scarlet

  7. I harvested three Sativas about a month ago. Cut them just above the first bottom node. They were grown indoors but I set them outside since we have good long days here right now. One of them turned brown and I pulled her. The second one has full green stalk with a small bunch of leaves just below where I lade my cut. But there is no signs of new growth. The third one is brown and dry near the top and has even split down for a bout an inch. Then four inches further down there appears to be a new shoot growing although it’s very small. Any suggestions here? Pics can be seen at

    https://www.dropbox.com/sc/82kay60s4pc3g2e/AABi9kUp5-fGi_A5e5Izrzwma

    1. Scarlet Palmer - Sensi Seeds

      Hello Wallstud,

      Thank you for your comment ? Unfortunately we cannot respond to grow questions on the blog, but we do have the Sensi Seeds Forum where you can ask a thriving community of gardening fans for advice, share your experiences, and see if your question has already been covered. I hope this helps.

      With best wishes

      Scarlet

  8. I took 60 clones from the most beautiful plant i have ever grown. Its a Williams Wonder that i grew from seed and it was Fermazied.I will never buy another fuckin female seed as long as i live.Every single clone that i cut went into flower in the prognator in less than a week. They died ever last one died. I have ordered regular seeds and ill take my chances on getting the Mother Plant i need to clone from. It cost me so much time and i near quit. Like i said near. But for you people that dont think you can revert the plant back to vegatative stage while that Williams wonder is today filled with hugh colas. still have 4 weeks to flower and the buds are as big around as a baseball bat.The smell is oh oh so good its not funny. Im going to revert my Williams Wonder back to veging as soon as i harvest her.The grass is fuckin deadly..Smokes a small bud from the bottom of my plant and no shit had to stay seated.

  9. Rednech Hillbilly

    Excellent article. I have a private reserve strain called Salamander which is no longer in production, and this technique saved her from permanent demise. Thanks for sharing, because otherwise I wouldn’t have my favourite sativa back in rotation. Cheers!

  10. hello. this article saved me three months of daily travel (to my secret/secluded crop) 60 miles plus! i harvested this crop in july (20 plants/9 lbs) and again yesterday, November3rd. i took your advice “seriously” and pulled 7 lbs/2 ozs the second time around. this strain was lemon diesel and the seeds were found in a bag, outside of a headshop in New Mexico. peace

  11. 1 plant can give you 10 lbs of bud a year indoor/outdoor or all indoor and the high gets better with age,the older the plant the stronger the high will be,but this is more for people and personal plant,indoor plant dont know seasons or harvests,over 40 years growing experience ,but now that its legal
    wow you can do it differantly ,grow more than you need so you can experiment ,do different things,take notes,light light light ,water when its growing ,less if it isnt let it dry out i remember humbolt weed $5 now would be $100 good seed is good seed ,seeds can last for ever,yes you can smoke leaf indo leaves will get you higher than alot of bud will 24hrs light needed
    trim trim trim cut the tops and 2 will grow cut those 2 and 4 will grow and so on short and bushy, constant trimimg, growth slows a litle but will continue and then faster and faster to much info:: secret info yes ,i think all info on net is full of shit ill give it 1/3 good info 1/3 bullshit the other 1/3 says nothing then 1/10th of all you might obtain as a gain in knowledge or not ,.this probably wont post just venting dont listen to me im full of shit…HA HA HA..

    1. you forgot to pinch stems like straws, it slows, then gets bigger. and super cropping. pinch till you hear it pop on stuff thats growing tall or near the top, { in flower the pinch method}

  12. Harvested amnesia haze auto.Legt it near a window. Well 3,1/2weeks later lots of pale shoots. Now its full all over again. As this is my med grow,it was a wonderful surprise. Yield was lower but hey it was an unexpected treat.yes I trimmed the whole thing down to 4 inches or so.now is a small height bush. It was great..Next year will try to do it ,instead of surprise look what happened. Thanks on article,never knew autos could do it.

  13. Jesse Boutet

    Im week 7 of 9 and im super excited to try this on these 12 UBC CHEMO. I wasn’t able to take any cuttings and as this strain is the original clone only i want to keep it alive. The friend who got these for me isnt around any longer and it was his connection. LOOKING FORWARD TO TRY IT.

  14. Jessica Barboza

    I’m a rookie to the fullest extent! I don’t have many lower branches as I tried to get them to grow roots to make clones, I don’t want to put my girls into flower stage until I figure out how to save and keep the mammas! Will they still regenerate even without those brances/leaves? Any info is amazing!!!

    1. Scarlet Palmer - Sensi Seeds

      Hi Jessica,

      Unfortunately, legal restrictions mean we can’t answer grow related questions or give grow advice on this blog. However, we do have the Sensi Seeds Forum where you can ask questions and share your experiences with a thriving community of cannabis and gardening enthusiasts, so please don’t hesitate to join the community!

      With best wishes,

      Scarlet

  15. Article very informative. My question is after a plant has been butchered, plant still barely alive, (thieving neighbor) is there a way to revive it please. It is just hanging in there but appears to be doing nothing. Am I able to revive/rejuvenate it at all. Thank you for time knowledge and time. Cheers Tasma

  16. Try using kid safe glue on the end of any cut help’s with the stress on the plant by stopping any exposure to the plants plumbing to air always worked good with me help’s with the regenerating process.

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    The Sensi Seeds Editorial team has been built throughout our more than 30 years of existence. Our writers and editors include botanists, medical and legal experts as well as renown activists the world over including Lester Grinspoon, Micha Knodt, Robert Connell Clarke, Maurice Veldman, Sebastian Maríncolo, James Burton and Seshata.
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