Re: Ludwigia glandulosa

> From: KB Koh
> Subject: Ludwigia Grandulosa
> I recently discovered that my single Alternanthera was actually
> a Ludwigia Grandulosa, according to Dennerle's book. My tank is
> 50gal with 80W lighting. Anybody know how many watts needed to
> grow this Ludwigia? Listed in Dennerle as full sun plant with
> 2 sun symbols but how much is full sun? Currently the plant is
> not growing well but recently perk-up a little since I removed
> the glass cover. Thanks in advance for any suggestion.

From what I learned growing the various Ludwigia species that I have,
and I suspect that L. glandulosa is one of those, I'd say that they
do well in moderately strong light. I found that these plants are
not resistant to brush algae attacks when there is not enough CO2;
perhaps this corresponds to insufficient growth conditions. They
would grow but slowly under 80w/49g. They seem to be growing the
best in my 250w/75g tank (light ~18" above tank) which contains the
soil substrate. Next time I would plant them in an even richer soil
substrate, thanks to advice from Paul Krombholz. They develop a
very nice reddish color with sufficient light and in a soil substrate
to help provide the necessary Fe!! BTW, this plant is not a very
fast grower compared to L arcuata.

BTW, there is an excellent article on the Fe benefits of soil
substrates in the Vol. 7 No. 4 of The Aquatic Gardener periodical by
Paul K.  I understand you can order back issues. Paul mentioned a
guy who mixed 1/3 cow manure, 1/3 sheep manure and 1/3 soil for
his substrate and was able to grow an Amazon sword plant in it for
quite some time. That story was in Here's Mud in Your Tank - 
Part 1, by Thomas E. Marquis (TAG, Nov.-Dec., 1991) Yet Another
shameless plug for "The Aquatic Gardener" :-)

Paul suggests a 50:50 mix of manure and soil and allow it to compost 
for a few weeks and then cover it with a layer of gravel. The
roots of plants provide oxygen to the substrate but according to
Paul, some anaerobic substrate is actually a very good thing for plants.
This allows Fe to be reduced to a more soluble state and in a continuous
soil substrate (no UGF plate) Fe can be continuously recycled requiring
little if any chelated iron supplementation!!