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grow and cut

When growing a bonsai trunk one needs to find the best way to grow a trunk fast. As discussed in why trunks grow thick, trunks grow because the plant grows bigger. This is direct conflict with the desire of keeping a plant small as a bonsai. So a number of different methods have been developed that will allow the plant to grow out, and subsequently still be usefull for bonsai. Here we deal with one of them, the ‘grow and cut’ method. Not that this is only suitable for species that easily create new branches on old wood. do NOT apply this on species like pines!

The general idea

Cut and grow

Cut and grow

If you have a plant that you would like to use as bonsai, but it is a tall tree that has been grown for use in a garden or forest plantation, it is not a lost cause. This is exactly what you are after with the grow and cut method: You leave the plant alone for a few years, untill the trunk gets close to the desired girth. Then you cut the tree down to a stump and let it grow out again. This process is repeated a few times untill a naturally tapered trunk is obtained. Make these cuts in late winter, when the tree is not growing. This way, all the energy stored in the roots can be used to grow a new leader. In general it takes at least three cuts to obtain a naturaly looking trunk.

Ratio’s and sizes

Typically, one would let the plant grow untill about two thirds of the desired trunk thickness has been obtained. That is the point at which you cut the trunk at one third of the desired final tree height. You can estimate the final tree height quite easily, taking into account the 1:6 to 1:12 trunk thickness to tree height ratio (read more about this). The next segment of the trunk you would let grow untill it is about two thirds of the trunk just below the cut. You cut this off at about one third of the height to be grown about the previous cut. Repeat this step at least three times. After each cut, you can expect a flush of growth, and many sprouts appear. Select the strongest sprout, or the one that is in the best spot. With a tiny wire place it up, in a natural curve to the original trunk. All other sprouts are removed, in order to focus all the trees energy to this one sprout.

Scarring

When a plant is cut, the bark below the cut will die off. Many books advice to make a slanted cut to facilitate this. However, it is not always certain how the bark will die-back and which branches below the cut will survive. By making a slanting cut, the cut is much bigger than when you would cut just straight through. This increases the risk of infection and drying out. I am therefor a fan of cutting the trunk straight, and letting the bark die-back naturally. A few months after making the cut (mid growing season) you can see the die-back line in the bark. At that point you can take away the died part of the trunk with a dremel or saw.

why it works

When one looks at a tree with a big straight trunk, one often thinks: This is very bad material for bonsai. This is however not true. By cutting low on the trunk, one forces a flush of new growth from which new leader can be selected. The new growth will add girth to the trunk below, and the bark will fairly quickly grow over the area that has been cut. As such, large wounds are covered. By the time the second cut is made, the largest part of the first cut is already covered with bark.

After each cut, one gets a slight bend in the trunk, exactly what one wants for an informal upright style. So do not worry too much about how the new leader is attached to the main trunk. The slight bends in the end will look natural, unless the branch is at a straight angle to the original trunk.

Grow and Cut

Grow and Cut

13 Comments

  • LuLu says:

    Hello,

    I was wondering when you cut the tree down, should you seal the cut to keep it from drying out? and if so, what should you use?

    thank you!

    ~LuLu

    • JelleFerwerda says:

      Hi Lulu,
      You are touching on a dificault issue. Some swear by sealing the wound. Others swear by leaving them open. Personally, I do not cover the wounds. I just leave a little stump, and remove the leftover bits once the bark has shown die-back to the new leader.

  • Michael says:

    When I’m performing the cut and grow method, am I using bonsai soil ( I.e. soil that lets water run through such as lava rocks) or allowing the tree to remain in good old fashioned dirt? I can see the positives in both and was just curious to your thoughts 🙂

    • JelleFerwerda says:

      Hi Michael,

      Interesting question. Personally, I put the plants in the full ground. Somewhere in the back of the yard. Nature knows best, so to speak. I think you could also say I am lazy. When the plant is so early in developement, why would I want to spend time watering them :D?

  • Neli says:

    Jelle,
    congrats on the nice blog??? Lots of useful ideas!

  • skipp says:

    Good info for all bonsai nuts. As an uninformed enthusiast; Why wont trunk cutting work with pine trees?

    • JelleFerwerda says:

      Pines typically do not produce buds on old wood. Also, removing a large part of the foliage may mean the death of a tree in some species, as the roots and foliage keep eachother growing, especiallly in pines.

  • Doug W says:

    When the plant is cut down to the stump, I assume that all green leaves are removed. Is that correct? Also, will this technique work with junipers?

    • JelleFerwerda says:

      Hi Dough,
      I do not purposely remove leaves. It will not work so well with unipers. most junipers have a hard time recovering from having more than half of the foliage removed. And most junipers do not through out foliage from older branches.

  • TheNowMovement says:

    I have a sort of unique problem with my Dawn Redwood bonsai… Its way young, maybe a couple years old, and it has no branches on the bottom half of the trunk. I’ve been trying to think of ways to get more branches downstairs, so to speak, but my research and ideas have come up fruitless. The only idea i have is chopping off the tree part with all the foliage and then replant this “chunk” of the tree and hope it grows new roots… has anyone done this before? If so, how would i go about doing this? Are there any other suggestions to sort of get your tree to get more branches toward the bottom of the tree? Thank you

    • JelleFerwerda says:

      Hi TNM,
      I have no experience with Dawn Redwood. Typically the way to get more branches lower on the trunk is by trimming a lot of growth from the top at a phase during which the plant is really health. that should produce a lot of buds. But each speciues has its own best way to do this. I am afraid I do not know the species well enough to give a definate answer.

    • Gabe says:

      I am just learning as well but I have seen people on youtube perform a thread graft to add branches to trees that are missing branches in places. Not sure how well this works on a Dawn Redwood but it worked well on this guys Maple.

      http://www.youtube.com/watch?v=Dqr_tM0rk1M

      Hope this helps you and others.

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