Pruning Marijuana Plants: Practice and Theory

Rambo February 21, 2012 27
Pruning Marijuana Plants: Practice and Theory

There are as many theories on the best ways to prune marijuana plants as there are strains; but all your pruning should follow this one simple rule: Effective pruning can and should direct a plant’s energy into growing the biggest and most resinous buds possible.

Before you start hacking away at your marijuana plants, you need a plan of attack. How you decide to prune your plants will depend largely on the growing method you chose and the size and shape you desire. Not all pruning methods are appropriate for ever growing technique. The sea of green method is going to require a much different pruning approach than lollipopping, super cropping or growing monster plants outdoors.

The art of pruning marijuana takes time, practice and careful planning;  but it can be reduced to two basic types: pruning to minimize branching, and pruning to stimulate branching. First the latter.

Giraffe Plants

Tall plants waste energy growing all that stem. They waste even more energy pumping water and nutrients all that distance to the top. The ends of the branches are where the buds grow largest. You want to make it as easy as possible for nutrients to supply those buds. Moreover, because of the inverse square law and leaf shading, very little light is even reaching the lower branches. This means that the lower area of the plant is little more than wasted space.

If you plan ahead, there are several methods you can use to prevent marijuana plants from becoming too tall. Increasing light, decreasing temperatures, training, and the use of hormone additives such as Bush Master can all be effective ways to prevent marijuana plants from growing tall and spindly.


You can also limit the height of plants with the pruning method called topping. To top a plant, simply pinch or cut off the top shoot just above a lower pair of nodes. The plant will now divide its energy into creating multiple tops from the remaining nodes and lower branches. You can top again later to turn each two new tops into four, and again, turning four into eight if desired. By topping in this manner, you reduce plant height and limit perpendicular growth. Because the branching occurs near the top of the plant, these new tops will get intense light and produce multiple medium size buds, instead of one large bud. While it can be fun to grow huge colas, they are susceptible to botrytis and tend to fall over if not properly supported. Because multiple tops can be trained to spread out, they can absorb more light and may produce greater yield.

Bush Monsters

Plants with excessively dense growth, called bush monsters, use a ton of energy to grow and maintain their maze of branches. Outdoors, bush monsters can produce huge harvests; but they are poorly suited for indoor growing. Because the plant’s energy is being divided in many different directions, the buds are all likely to remain small and sparse.  Due to poor light penetration, interior branches will drain plant resources with minimal yield. Bushy plants also reduce airflow and trap humidity under the canopy, creating an environment hospitable for insects and fungi such as powdery mildew and botrytis. These pests are more difficult to control with spraying, due to the plant’s dense foliage.

Thinning Branches

To prevent bush monsters and optimize your plant’s productivity, carefully select which branches to promote into big bud yielders and which branches to remove. The number of branches you grow to maturity should match the size of the available growth area and the strength of the root system. Plants grown with very little space to branch out, as in the Sea of Green method, may require that all but the main stem be removed. On the other hand, outdoor plants or indoor plants with room to spread out may only require the pruning of the lower, shaded branches.

Here is a video demonstration on thinning branches on indoor marijuana plants.

Avoid Excessive Pruning

Excessive pruning causes stress and should be avoided. Do not prune without a reason. Every time you make a cut, the plant must spend energy to heal itself. This is energy taken away from growing and flowering. Prune only what needs pruning.

Bugs and Pests

Every cut you make exposes the plant to infestation by insects and fungi. Plants use even more energy to fight off these pests than to heal from pruning. Some articles and forums suggest the use of tree wound sealer. It makes sense that a product used on trees would work just as well on marijuana plants. However, significant scientific research has proven that commercially available tree wound sealers are purely cosmetic and do not help the plant heal at all. In fact, these products can actually slow down the healing process. If a cut is showing signs of infestation, be sure to remove the infested area immediately and treat with a fungicide or bug treatment.

Stop the Bleeding

Avoid pruning in a way that makes the plant bleed. When possible, it is better to pinch off leaves and branches than to make a clean cut. Fingernails crush the cells rather than slice through them. This reduces the plant’s bleeding and facilitates healing.  If your fingernails are not up to the task, try using a sterile but dull pair of wire cutters or needle nose pliers. If you have ample time, the very best method is to pinch or bend a branch just until it dangles, then leave it dangling for a day before removing the branch. This gives the wound time to heal without fully exposing it. Not all growers have the time for this approach.

There is much more to pruning, but these are the essentials.  If a picture is worth a thousand words, then a demonstration video should yield volumes. We are working on a few more of those so check back soon.

Tools of the Trade

For those of you who are interested, here are some links so you can use to purchase a few of the tools you may need. As with any chore, having the correct tool for the job makes life a lot easier.

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  1. wolffdw February 22, 2012 at 8:54 pm -

    I have read each one of your information papers and must say, they are some of the best reading out there. I am just a learner now but will, very soon be a beginner grower. Much of what you say makes since and is educational. I am very interested in the construction of the perfect but economical grow room. I know I can buy a tent and get started for a budget at the upwards of $3000 but I also know tents fall apart after awhile. I have indeed seen many videos on the web with many different designs but would like a video from you as I said before, you break it down for the new guy to understand.

    • Rambo February 22, 2012 at 9:30 pm -

      Thank you. What an amazing complement. We will certainly be doing some grow room construction articles and video in the weeks and months to come. How large is the grow room that you are planning? If you have specific questions, feel free to leave them here or join our forum.

  2. Frank July 15, 2013 at 6:21 pm -

    Thanks for the info , I too live in Northern Cal in a very small town . The cops been driving through every evening , they say if they see it it’s gone ! So I’ve been pruning trying to stay under my 6 foot wooden fence . I think I may have gotten carried away when pruning then I got really down when they went into shock . Seeing everyone else’s 5 or 6 feet mine only being around 3 or so . Your article shed some light for me , seems the more positive I felt the more they grew . There still short but much happier and being the middle of July they still have a month to bush up wich there doing now . It also didn’t help them with my water being around 8 PH . Thanks again

  3. Newbie July 30, 2013 at 11:25 pm -

    I just have one question and please excuse my lack of knowledge in this subject but this will be my first plant ^.^ and i have very limited space to grow it as i am trying to keep it on the down low and anyway how much pruning is too much pruning?Thank ~Newbie

    • Newbie July 30, 2013 at 11:35 pm -


    • Rambo July 31, 2013 at 7:16 pm -

      I wish I had an easy answer for you, but I really don’t this is something that I think you just learn with trial and error. In my opinion, prune as little as possible. You would be better off starting the plants later and training them.

  4. Newbie July 31, 2013 at 11:47 pm -

    Thank again Rambo!!!!

  5. Cali August 17, 2013 at 12:45 pm -

    Hello everyone and thank you so much Rambo for all the wonderful information. I’ve successfully completed an indoor grow the end of last year and this year I thought I would try outdoor also, but I have to say outdoor seems to be so much harder for me. I know dont make much sense.. It seems my plants have a light shortages (growing tall with few nodes sites) and I know it can’t be lack of light because where I live its supper sunny even a bit hot,, maybe could too hot of temperature cause this problem?? As for my plants they are very green a couple have really strong stocks and other then not being very bushy look really healthy.. I would love to know your thoughts of this problem and any suggestions you might have for me.. And thanks again on all your info. ~C@li

    • Rambo August 23, 2013 at 11:22 pm -

      If they look healthy they probably are. The spacing between branches can be effected by a lot of things and does not mean you have a problem. At least as long as they have room to grow.

  6. Daniel August 18, 2013 at 6:20 pm -

    Prune when the leaves become useless and the stems have no “juice” flowing through them. Waste of energy and makes the flowers pop up FAT from where the fan leaves were 😉

  7. Daniel August 18, 2013 at 6:22 pm -

    Also… Pruning is a way of making your plant “look good” Think of it like a haircut for your plant but starting from the bottom.

  8. will August 24, 2013 at 6:25 pm -

    I have my first plant and it is about 1 1/2 ft tall and it looks great. I havent done anything to it yet except for watering it. Should I do anything to it like trimming. Didnt know and was wanting to find out. Thanks

  9. sarrah September 18, 2013 at 5:18 pm -

    Rambo, I am growing my very first ever plant outdoors in a pot. It is a clone, and is now in a 10galon pot.D It is beautiful. I was late getting it, (july) . There are many flowers (?) it is aprox. 2 1/2 feet tall, very green. I did not trim anything and it is Very dense and bushy, all the way down the plant stem to just slightly above the soil. There are many flowers on the lower levels. MY question is: 1. Should I trim away some of the leaves to expose the lower flowers to more light. 2. Will this harm the plant? 3. if I do trim off some of the flowers, can I use them for anything or are they now garbage?

    Note: sorry if these are silly questions, but I have been looking all over the net for answers, but have become weary of all the reading, without finding clear, specific answers. Help!

    • Rambo October 2, 2013 at 8:43 pm -

      If you only have the one plant I would just leave it alone and let it do it’s thing

  10. sarrah September 18, 2013 at 5:31 pm -

    I did pinch off the very top center leaves when it was still I the 4 gallon pot. (Something I read early in my research.) I am not a user, and my purpose for growing this plant is to make medicine for my arthritis, and to make edibles for other health conditions.

  11. sarrah September 18, 2013 at 5:35 pm -

    p.s The picture in your article under bush monsters, looks just like mine 🙂

  12. haze October 23, 2013 at 9:08 am -

    I have fi growsnts in one 5 gallon bucket all five of them have grown 3 inches is that good or bad to have them together and i have them outside will it be ok if i bring it indoors so i can prevent bugs and pest and infestation and i have a heating lamp is that ok

    • Rambo October 29, 2013 at 7:12 pm -

      If you want me to put some effort into answering your questions, please put some effort into asking them them clearly. I can barely understand your questions. One plant per pot, and yes you can bring them in but that won’t prevent pest problems, in fact you will likely have bigger pest problems inside your house than outside.

  13. hamzah November 1, 2013 at 12:11 am -

    yo rambo
    i got my 8 month old plan dropped and sway, the plant stayed in same place but the roots harmed a litter
    so i was outdoor growing then i moved it indoor
    and now it appears a small white dots on the green stem
    what should i do and how can i show you some pictures to help me knowing her sex

    • Rambo November 19, 2013 at 6:05 pm -

      you can repost with photos in the forum

  14. kevin huyton December 2, 2013 at 10:17 am -

    How do I register to become a member plz Rambo

  15. bigbush March 24, 2014 at 6:55 pm -

    I have my plants started inside so there healthy to put out for spring but I just need to know how many times do I need to top to have a huge monster plant??

  16. Mslina March 28, 2014 at 7:06 pm -

    Hi, I had a question about when to start the pruning process, and how do I know when and where to cut to start flowering? Do I need to pollinate it? If so how?

  17. Nicole April 24, 2014 at 11:42 pm -

    I’m a new be, too… I’m trying to trim.. and I don’t. Get it. Do I take off the little leaves that’s growing on the boddems of the stems or what.. HELP.

  18. jerry June 6, 2014 at 9:42 am -

    Got some pics I’d like to post just wanna see how I am doing for my first time.

  19. Gary July 12, 2014 at 4:18 pm -

    Do you ever trim large fan leaves from the top to allow light to the lower flowers?

  20. Cam August 15, 2014 at 8:03 am -

    Hey Rambo, seeing this is my fourth year growing outdoors I have had a good amount of time with trial an error. When it comes to pruning I always thought to do it while the plant was young or before it starts to flower. I have never trimmed or topped a plant while in its flowering stage. My question is: Would topping a plant a such a late stage of its life cycle effect the flowering, or would it do exactly what you said by spreading out creating medium size buds. I just don’t want to cause stress and have no flowers at all. Thanks so much