cornus kousa satomi, red

Discussion in 'Cornus (dogwoods)' started by Daniel Mosquin, May 28, 2003.

  1. Daniel Mosquin

    Daniel Mosquin Paragon of Plants UBC Botanical Garden Forums Administrator Forums Moderator 10 Years

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    Vancouver, British Columbia, Canada
    The following was received via email:

    I am hoping you can help me. I have planted this tree in a very large concrete container on my patio, the conditions are very good for it here - Kelowna- on the lake, sheltered from the direct sun. My question is this, do I need to fertilize this tree because it is in the container? If so what should I use, I assume I'm a little late for this, but better now than not? The leaves have come out but there are no flowers yet. Can you offer any other suggestions to help our new green friend?

    Thank you.
  2. Douglas Justice

    Douglas Justice Well-Known Member UBC Botanical Garden Forums Administrator Forums Moderator VCBF Cherry Scout Maple Society 10 Years

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    Vancouver, Canada
    In general, plants in containers need more attention than plants in the ground, as their roots have a finite area from which to extract water and nutrients. Such plants may benefit initially from the excellent drainage and superior aeration afforded by the container, but these characteristics are eventually overshadowed by root crowding and compaction and the related problems of reduced moisture and nutrient retention. The smaller the container, the more quickly these issues come to the fore.

    Another problem with respect to container size is heating and cooling. Small containers heat and cool more quickly, so exacerbate the effects of freezing and drying. As long as the container is relatively large, it will effectively buffer all of the above-stated adverse effects.

    As organic matter oxidizes in the soil (and is lost), it needs to be replaced. The easist way to accomplish this is with the periodic addition of a thin layer of compost -- leaf mould and kitchen compost work well. Inorganic fertilizer additions are almost always unnecessary and wasteful. Slow trees growth is always easier to manage in a container, anyway.

    An issue that is often overlooked is the pH of applied water. If your water is alkaline (hard), the soil in the container will eventually become alkaline and unsuitable for the growth of Cornus kousa and many other landscape plants. If your water is hard, you may need to treat it, or try growing plants that are more tolerant of alkaline soils.

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