Yes, I too would like to know as one of our pine experts out
here includes it heavily in his soil mix.

Kitsune Miko

Bill Watkins wrote:
Jim, you mentioned that using a fertilizer such as Osmocote on
bonsai can be a bit dangerous and should be used sparingly. Would
you please explain how it can be dangerous.

================================================== =========

1. There is no electronic timer that tells each fertilizer
pellet (of whatever size) that "now is the time this plant needs
so much of X, Y, or Z." Whether fertilizer pellets dissolve is
conditioned on the temperature and the moisture level in the pot.
Since we keep our pots fairly moist -- moister per unit of soil
than you would normally find in a garden -- there's always a
"dissolve now!" signal being sent. Add to that the heat from a
summer in most of North America (and pots get hotter than yard
soil!) and you are doubling up on the signal. You can end up
with a more-or-less severe build up of phosphorous in your pot,
depending on which pellets open when. And if you add
supplemental fertilizer (as many do) how do you know when your
tree(s) need something and when you've just given them a large
dose of opened pellets?

So you have NO control over when, where, and how much nutrients
reach your plant. This is OK in the wide open space of a garden.
In a pot, it's more serious.

2. If you supplement with other fertilizer over the course of
the growing season, you can be exacerbating this problem. If you
don't, you probably will be ending the season with not enough
fertilizer for over wintering.

3. Since the fertilizer is designed to be randomly triggered, in
a cool year, or in a cooler climate and shorter growing season
than MANY of us have in North America, there could be a sizeable
amount that doesn't dissolve over the course of the growing
season. This means the possibility of a sudden dose of old,
possibly spoiled fertilizer in winter. (I haven't noticed this
problem, but I have heard of and from others who have, but I
never have a cool enough summer to worry about any of it not
dissolving.)

4. Since the technical side of bonsai is about controlling
growth -- think about it: we control our plants in many ways --
why would you allow your fertilization regime be completely
random? Mature trees do NOT need a major influx of nitrogen in
late summer -- which is likely (probable!) with randomly opened
palletized food.

5. It's not a danger, but those little round, yellowish balls of
used and unused fertilizer are unsightly (and also resemble some
kinds of insect eggs).

This stuff is fine for yards (and probably for dime-a-dozen
houseplants in pots) but not ideal for bonsai.

And I know I'm about to be deluged with
"I've-been-doing-it-for-years-and-have-had-no-problems messages."
I'll reply to them now: "Fine. But _I_ won't."

Jim Lewis - - Tallahassee, FL - Only where
people have learned to appreciate and cherish the landscape and
its living cover will they treat it with the care and respect it
should have - Paul Bigelow Sears.

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