Discussion in 'Soils, Fertilizers and Composting' started by barbgup, Jun 11, 2004.

  1. barbgup

    barbgup Member

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    Vancouver, BC
    What is the effect of putting oyster shells or other shell on potted plants???

    Some plants thrill and grow very fast - Why??

    Some plants will die - Why???
  2. mr.shep

    mr.shep Well-Known Member 10 Years

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    San Joaquin Valley, California
    Hi Barbgup:

    Most people will use oyster shells to add Calcium either to correct a
    chlorosis problem or thinking that the oyster shells will help improve
    drainage or to improve soil pH. For usage on potted plants it depends
    entirely on what plant and where is it grown such as indoors or outdoors
    and the relative size of the shell, either large and coarse or ground almost
    into a powder. There are plants that respond well to oyster shells such
    as Azaleas but it seems best to use the oyster shells for Azaleas in the
    ground. I believe right off hand that Blueberry growers use oyster shells
    as well. On the other side of the spectrum are plants that do not like the
    oyster shells at all such as Quercus palustris that tends to have a strong
    aversion to Calcium. Oyster shells can contain as much as 36% Calcium
    which is quite high a percentage. Some plants do well and some will be
    killed off due to the plants sensitivity to mega doses of Calcium. I would
    prefer to use oyster shells on select "acid loving" plants grown outdoors
    rather than on alkaline tolerating plants. I would not use oyster shells
    on ornamental plants at any time as the microbial breakdown of the
    shells will take too long and the release of so much Calcium cannot be
    adequately countered by the indoor growing plant. What happens when
    we give a plant too much Nitrogen? We kill off root systems. Well,
    the concentration of Nitrogen is generally much less than the amount
    of Calcium from the oyster shells and perhaps other shells as well
    applied to the roots. The root systems in many cases will not be able
    to handle so much Calcium, either all at once or even at timely intervals.

  3. oyster shells

    Hi, would you put oyster shells as mulch around Lavendar plants?

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