Cornus kousa chinensis

Discussion in 'Cornus (dogwoods)' started by johnnyjumpup, Apr 7, 2008.

  1. johnnyjumpup

    johnnyjumpup Active Member

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    I just bought a 30 inch tall c. kousa chinensis from UBC garden shop. It looks like a twig that has been topped at 13" and has produced two upright shoots either side, so trunk about finger sized. I had in my mind that the chinensis grew eight feet tall by six wide now that I think about it the named varieties (Summer Stars, Milky Way) was probably what I remembered. I see on the label now that I am home in the West Kootenays) that mine grows to 20 feet which means I have to rethink where to put it.

    Can anyone tell me how tall and how wide this will get and how many years to maturity and that nice layered look? How much growth does it put on per year? Is it better in morning light, afternoon light? I have quite a bit of shade so am quite protective of what sun I have. An eight foot shrub would have been perfect, even ten.

    Is it possible to prune this shrub to keep it relatively short (8 feet) without ruining the shape?

    Any tips most appreciated. PS am Zone 5/6

    Thank you
     
  2. Ron B

    Ron B Paragon of Plants 10 Years

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    A Kousa in Seattle had an average crown spread of 41' in 1987. Another was 41' tall in 1990. The Chinese variety has extra horsepower, most modern cultivars belong to this. Heading back to control size is not practicable as, like other tree-form dogwoods the shape of the branches doesn't lend itself to this. (Sometimes an existing specimen can have a few branches that are in the way carefully cut back to suitable side branches to shrink it a bit, but repeated heading back to keep a 40' dogwood 8' tall yet attractive is not possible).
     
  3. johnnyjumpup

    johnnyjumpup Active Member

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    Hi Ron,

    Forty Feet!!!??? Will colder and higher altitude cramp its growth? How old was that 40 footer? I have found two references for 22 x 15 feet. I'm at el. 2100 feet.
     
  4. Ron B

    Ron B Paragon of Plants 10 Years

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    Plan on about a foot per year, once getting up a full head of steam and while this is maintained. Many think of sizes for trees that are really those of shrubs. A representative range for small trees is 15-35', your Kousa is definitely a tree. Probably a seedling and definitely affected by your site conditions, it could mature within 15-35' or it could grow taller.

    Lots of false information is promulgated about garden plants and gardening. When looking at sources giving heights and spreads always look to see if a time frame is associated with those sizes - and keep in mind there may be one involved even if that is not stated somewhere in the reference. And remember that growth of individual specimens varies with their genetic makeup and the conditions they are exposed to.
     
  5. smivies

    smivies Active Member

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    An 8' maximum height is unrealisitic with Cornus kousa & 40' is not likely for most specimens, even in old age. Plan on a mature 15'-20' that will look best if it is not pruned for size management.
     
  6. johnnyjumpup

    johnnyjumpup Active Member

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    Thank you both for info. I will find a suitable spot for it. I am all for letting it find its natural form. How soon would it flower - 5 years, 10 years? Does it grow up first, say to 15 -20 feet, then spread sideways as it ages? I have never seen one in person though I plan to see if I can find one at Van Dusen or Spokane. I see there are some in Stanley Park (Trees of Vancouver, good book).

    Spokane is about the same elevation as us but drier and more open, not mountainous.
     
  7. smivies

    smivies Active Member

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    Young ones here are ~12' and vase shaped. Vertical growth is still fairly rapid, side growth not so much, and they flower prolifically. They were planted ~8 years ago and I expect they'll begin to develop a more mature form in the next 5-10 years.
     
  8. johnnyjumpup

    johnnyjumpup Active Member

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    OK. It's a tree with a trunk that will grow to 15-20' at least. I can deal with that, now I've got over the shock of it not being 8 feet high. Will it start to bloom when it's 12' high? Nine years. I am looking forward to seeing it bloom.
     
  9. smivies

    smivies Active Member

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    Standard nursery stock in a #5 container will bloom first year. May bloom when smaller as well.
     
  10. Gordo

    Gordo Active Member 10 Years

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    Generally speaking, seedling stock will take considerably longer to bloom than grafted specimens. I'd guess 8 - 10 years of age on average for the former. Also, blooming will tend to be more prolific when planted in a sunny exposure.
     
  11. silver_creek

    silver_creek Active Member

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    Flowering of seedlings can vary widely- I've seen 3 year old trees bloom, and some that had reached 10'-12' without a single flower. When they do start blooming, the bloom is usually quite prolific.
     
  12. johnnyjumpup

    johnnyjumpup Active Member

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    Hi,

    Thanks for the input. I don't see a graft so I guess it's a seedling. I hope it blooms earlier that later, but at least I know what to expect. Something to look forward to.
     
  13. Chooch

    Chooch Active Member 10 Years

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    Location:
    SW Ontario 65 miles west of London / 33 miles sout
    I grew my Cornus Kousa from seed and it flowered lightly in the third year of growth . The tree is now 8 years old and approx. 8' tall ( this was the most vigourous growing seedling from that batch and many others aren't even one third of the size )
    The Original plant that I acquired seeds from is located in Ridgetown , Ontario and it stands around 15' to 20 ' tall with an equal spread .
     
  14. johnnyjumpup

    johnnyjumpup Active Member

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    Thanks Chooch,

    That's encouraging. I am willing to wait a while but I'd really like to see the bloom shape and colour in person.
     

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