I've been using pea gravel, covered by 2 inch river rock for several
reasons:
1) Koi don't root around in it, like they did soil containing pots (they are
benthic feeders, are love to root around in the dirt looking for munchies)
2) If it spills, it's a lot easier to clean up than soil, and they do spill!
3) It's easy to divide, and prevents loss of material clinging to roots
(dirt clings more easily than pea gravel which washes away, usually without
any root ball damage..
4) There is much less compaction (of soil base), so less H2S and methane
production
5) it's really no heavier than clay soil
I did the studies a few years back comparing lily growth and bloom in pea
gravel vs. soil.
You need to be sure to use a slow release fertilizer that supplements agents
soil usually contains (minerals, etc), not just the N, Phosph and Potash. I
use what Longwood gardens uses.. highland rim. if you fertilize there is no
difference in plant vigor/blooms. if you forget to (as I have done), there
seems to be less blooming, but no difference in leaf production.. that's for
lilies.
I have always had my marginals in pea gravel, without fertilization, and
they do great.
Happy ponding,
Greg

--


"Mike Miller" wrote in message
news:5l62b.245009$YN5.164904@sccrnsc01...
I'm planning an expansion of my pond next year to deal with some issues I
created. One of them is poor plant growth in marginals that are in clay
soil but with no additional fertilizer.

One one side of the argument is plants in clay/soil do better, but might
not
be able to get at nutrients present in the pond, thus allowing string
algae
to outcompete them as the clay "keeps" the nutrient flow away from the
roots. (BTW, I'm not presenting this as fact, just trying to figure
things
out!). I have to wonder about this when I see arrowroot growing huge in
the
natural ponds around here, yet my in-kitty-litter arrowroot is but a puny
shadow (well, it's also in a pot...). One could fertilize and they would
do
better, but why add nutrients here if the pond is already producing SA,
meaning there is excess N and P in the pond already? (I, like many of
you,
add K regularly)

On the other side is that plants in gravel or gravel beds, or just tossed
into the water can take up nutrients in the water faster or better,
allowing
them to grow better and (hopefully) out-compete the SA.

I suppose pot size per plant would also be a factor here - perhaps my
marginals need bigger pots? But I do know that the WH and other
toss-them-into-the-pond type plants (parrot feather, et al) do fine.

So, how about a poll. Whose marginals are in gravel and whose are in soil
of some type? How well do they grow? Do you fertilize, or add K at all
to
your pond? Maybe this could be a useful thread to collect some real life
data.