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hebertju56

Close trees in containers

Hi everyone,
Last summer I built a container garden on my terrace. I'm on the third floor in Canadian Zone 5, so when I'm prudent I plant Zone 3 and below. I have large containers (2 x 2 x 4 feet) in which I have planted some trees. But I might have place for more. I want to know if there is a limit to how close I can plant 2 trees in different containers. I have an elaeagnus angustifolia in one and would like to plant a carpinus caroliniana in the container next to it. The trunks would be about 3-4 feet apart. Do any of you see a problem to this? Keeping in mind that in my climate and in containers the trees stay pretty small (plus I'm planning regular repotting and root pruning). Thanks for any input!

Comments (6)

  • Cliff Pruitt
    9 years ago

    I'm still very new to this so take this answer for what it's worth, but I think that your answer ultimately depends on what you mean by "limit". In nature trees will grow extremely close together and grow successfully. Whether or not the trees themselves consider this to be "ideal" may be another matter. In your case, the trees would not be competing for water or nutrient resources, but if they are close enough they may compete for light. I'm new enough at this to not know specifically how this would effect your situation, but I imagine that as the trees grew they would tend to grow more on the "open" sides while being more restricted where their branches started to come into contact with each other. If light is scarce and one blocks the other out entirely, you might find that one of them grows poorly.

    If I am understanding you correctly, you want to plant new trees in new, separate containers. If that is the case, I think that you at least have the luxury of moving the containers farther apart in the future without re-potting if you feel it's necessary. That is, assuming you have the space to move the containers.

    I'm sure someone here has more experience than I do and can offer something a little less speculative.

  • ysrgrathe PA 6b
    9 years ago

    This link provides some good examples. Note that the degree of spacing needed is also dependent on the size of the tree and the desired form.

    Here is a link that might be useful: nursery spacing

  • tapla (mid-Michigan, USDA z5b-6a)
    9 years ago

    I pretty much agree with Cliff, but let me expand a little. There won't be much competition between the plants for water and nutrients up to about the point in time where root congestion is advanced to the degree the root/soil mass could be lifted from the containers intact. From that point forward, until you repot (which includes root work to relieve the congestion) the more genetically vigorous plants (both between and within species) will retain a greater portion of their genetic advantage than the plants less genetically gifted with vigor. The more severe the root congestion becomes, the more obvious you should expect the disparities in vigor to be reflected in the plants' state of vitality. Remember that vigor and vitality are different. Vigor has to do with what potential Mother Nature endowed the plant with (genetically) and vitality is a measure of how well the plant has been able to deal with what she (or you) throw at it in terms of cultural conditions. Extremely vigorous plants can suffer from reduced vitality and die from the stress of cultural limitations.

    Ideally, you would reduce competition for light to something that isn't much of a factor by way of selective and directional pruning. IOW - you'll remove the branch that contributes least to the composition in instances where there is competition for light and space. In a perfect world, you would be doing this with a plan that takes into account not only the eye appeal of the planting taken as a whole, but the health of the individual plants as well.


    Al

  • Julie (Montreal, Qc Canadian Zone 3-5a) Hébert
    Original Author
    9 years ago

    Thank you so much for your help everyone. I am planning on putting the elaeagnus in 'front' of the carpinus, where it will receive most of the sun and protect the carpinus a bit from the hot afternoon sun. So if there are no other parameters to worry about (like trees of different species not appreciating touching each other), then I'll think I'll go for it. With respect to Al's comment about vitality; I have to admit I am concerned about this, for ALL my plants. I have no option but to plant my 'little green babies' in containers, so they will all be living with some form of stress, right? Even if I take good care of them, is there an ethical limit to what I can impose on the plants? Should a carpinus ever be planted in a container? Can it be 'happy' there, or should I just be satisfied when I see that it has good vitality?

  • tapla (mid-Michigan, USDA z5b-6a)
    9 years ago

    I guess, deciding what's ethical is an individual thing, but I have no issues with things like starting cuttings to use as root grafts and then tossing the whole top of the plant after the graft has taken. If you kill a plant, even by willfully ignoring it, I'm not going to think less of you as a person or even a grower.

    You should be able to successfully grow virtually all trees that grow in the ground, in containers. The key to doing that is providing cultural conditions that limit the plant as little as possible, and that's where some of the challenge lies as well.

    Sometimes, there are some allelopathic considerations when genera are mixed, but not always, and sometimes it might be so mild that it goes unnoticed. I'm not sure how you'd find out whether there are allelopathic interactions between the species you'd like to mix, but I wouldn't let that stop me from putting the different genera together and trying it if I had a yen to do that.

    Al

  • Julie (Montreal, Qc Canadian Zone 3-5a) Hébert
    Original Author
    9 years ago

    OK thanks Al. I don't know how I would find specific allelopathic interactions so I guess my garden will be a bit of a laboratory-we'll see. I suspect that there would be none between these two species since they have such different geographic origins. As for the vitality of my trees in containers, it will also be a bit of an experiement (a long one), and the best I can do is take good care of them.
    Cheers
    Julie