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Re: growing Lobelia cardinalis

Hi there,

I have been a Lobelia C.  fan for many years. Herewith my experiences (
YMMV ) .

A little warning for new Lobelia growers. When Lobelia is purchased from a
store it has probably been grown emersed. It has longer leaves than the
usual round shape. the lower side of the leaves are red and the stem is
less pronounced. It almost looks like a rosette plant. Be prepared; the
plant will loose most leaves ans start outputting nice round light green
leaves if conditions are allright.  When  obtained from a fellow aquarist
you probably receive submersed forms.

1: Growing lobelia in less than high light. : perfectly possible. I have
tried to grow lobelia in a low/medium light set -up for years. The plants
were growing very slowly and easily  lost their lower leaves , the stems
got pretty thin and leggy too. As a substrate I used waste laden gravel
only . Basically  not a real success.
It is only since I  changed my low maintenance tank to a fertile substrate
lobelia became a success . Instead of gravel only , I have a mixture of
clays, peat and some fine soil mixed in with the gravel. The tank is 125 cm
X 40cm X 40 cm with 1 triton T8 and 1 gro-lux T8 , old fashioned ballasts,
and few fish.  Since this new substrate the Lobelia has taken off very
well. Not as well as in my high light high tech set -up but nevertheless
growing. Thanks to the digest and the krib I also started adding some K and
Fe +traces ( little ) to the water which helped avoiding the older leave
drop and made leaves greener . The rich substrate also allows for thicker
stems, greener leaves and shorter interleaf nodes. In these conditions , my
lobelia grows rather slowly but strong and steadily. The tank has no real
high output CO2 system although I add some CO2 through a sochting
carbonator. ( citric acid on some carbonate I believe ) . Since the tank
has not so much light it is doing just fine by adding these minimal amounts
of CO2 to avoid biogenic decalcification and Ph rise . ( I am not so
convinced of the carbonator system, but in a low light set-up it may just
give that extra kick ) .
I like to mention that this low maintenance set-up grows Aponogeton like
crazy. ( it is also a lower temperature tank without substrate heating of
any kind ) . If I up the temperatures, the Aponogeton does not do as well.
I feel that the Lobelia requires similar care when in low maintenance
Above explanation is based on my experience, I do not say Lobelia needs a
fertile substrate but it definitely helps. Like this I have less roots
shooting out from the stem above the gravel line and stronger bush of roots
under the gravel line,ymmv.

2: Growing Lobelia in high light: Provided the conditions generally
described in this forum for higher light/energy tanks no problem.
Sensitive to lack of K.
( my substrate is far less rich in high light set-ups , plenty of laterite,
clays and substrate heating  though )

3: Propagating L.Cardinalis.

By topping and replanting the topped shoots. 2 new shoots will sprout out
of the top undamaged meristem . ( growing point, I don't know the english
name ) .

By growing and propagating  the emersed form: At one point I wanted to
propogate Lobelia more quickly in order to make a nice sloping group. I
therefore adjusted about 5 shoots to emerse growth by planting them in pots
with soil and slowly lowering the water level while keeping air humidity (
cover the pot or tank with foil ) . In spring, the adjusted shoots where
then planted  in the swamp area of our outside  pond . During the summer
the plants grew up to large size( more than 50 cm high ). Late summer the
plants produced the beautifull flower stalks  the plant is named after (
cardinalis from cardinal red )  .
At the end of the summer the plants had grown big rosettes with several new
side shoots. After cutting the flowers off ( seed propagation is something
I want to try another year so I cut the flowers so all energy goes into
plant mass  ) I bent the stems to lay flat on the pond swamp soil. ( hold
in tight contact with the soil with plant hooks ) . After a while most of
the nodes send out growing points. When the growing points had a few leaves
and roots, I brought them back into submersed form by flooding the swamp of
the pond. One month later they stopped growing because days were getting
too short and cold . At that time I just pulled out all the shoots and
planted them in a tank again. The plantlets shed leaves again. After
another month I had more then one hundred fresh plantlets with fresh
submersed leaves. The whole process lasted from early spring till beginning
of winter. So it is a lengthy procedure compared to submersed topping
propagation but the yield is much higher. ( one needs a swampy area and a
good summer though (if you live in colder climate like W. Europe ) .

For reference I like to mention that there are at least 2 varieties . A big
one and a small one. My impression is that the larger variety grows better
in low light set-ups than the small variety  . There may be more varieties
in the pond business:  L. Cardinalis is sold there for its red flowers . I
found several sizes in pond shops but I have no clue what they would look
like in submersed form. At one stage I tried another pond  Lobelia species
in submersed form. It did adapt but the leaves where pointed and stems
leggy, obviously not so nice in the tank so I stopped that experiment.

Hope this helps all Lobelia fans.

suisoman Dirk