[APD] Re: hydroponic emersed culture (Cavan)

["William J. Wells" <wwells1 at concentric_net>]

Cavan wrote:
> Hi everybody
>
> I've been growing Hygrophila corymbosa, H. difformis,
> Limnophila aromatica (aka Gratiola), and Echinodorus
> tenellus out on the deck this summer.  I have a few
> questions.  
>
> 1.  How "rich" can you make the water you feed the
> plants?  I'm not worried about algae or anything here,
> so can you just really go for it?  The aromatica has
> grown a lot more since I started adding macros and
> Flourish to its water (lots more side shoots and
> flowers).  The other plants are all growing out of a
> big salsa jar filled with Flourite and dirt.  They
> have been getting the same water as the aromatica. 
> But, although the plants are healthy...
I have found the emersed aquatic plants I grow can do quite well in pots 
with regular potting soil.  They do benefit from the addition of 
fertilizer.  You would have to add a lot of micro-nutrients to overdo it.
For macro-nutrients you can use a regular house plant fertilizer, just 
follow the directions on the package and you won't overdose the plants.


> 2.  Why haven't any of them grown much above 8 inches
> or so?  
My emersed aquatics don't tend to get as tall as the same ones in a 
tank.  The bright light outside should make the internodal distance 
smaller so the plants will be more compact and not be trying so hard to 
reach the light.  Mine tend to reach a certain height then bloom or send 
out side shoots.

> All seem to have adapted to outside
> conditions, but I thought they would have been much
> larger by now.  As long as a plant has enough
> nutrition, does it matter if the roots are a little
> crowded?  I don't think that should be a problem at
> this point, but could it?  For the most part, my thumb
> is only green below water.  I'm ashamed to admit I
> have some sad looking house plants.  
Plant growth can be restricted if they are root bound.  Knock one out of 
its pot and see if it is a solid mass of roots.  I have found that roots 
can fill a small pot very quickly.

I have my pots sitting in a deep tray with a water depth that ranges 
between 1/2 to 4 inches (usually around 2 inches).  The soil surface is 
always above the top of the water, although that isn't necessary.  The 
water in the tray does get thick with hair algae all the nutrients in 
the soil and the sunlight really make it take off :).


> 3.  What might the emersed temperature tolerance of
> those plants be?  It's starting to get cool around
> here.  
The Hygrophilla will still grow well in the upper 60's F and will 
survive short exposure to colder temps as long as it doesn't frost. 
Growth will slow down greatly at lower temps though.
I don't know about the Limnophila aromatica, but I have had Echinodorus 
(other than tenellus) survive exposure to 55 F for about 36 hours and 
survive.  It wasn't happy about it, but it did pull through.


> 4.  Is the air inside an average house too dry for
> them?  I'm wondering if they could make it as house
> plants (which might spell their doom by either dryness
> or neglect).  
As long as they are sitting in water they will do OK.  They will be 
happier in a terrarium though.


> 5.  I suppose I could move them to a covered empty 20
> long and leave them in a well lighted area.  I do have
> a terrarium going, but emersed plants seem to do a lot
> better under the sun than even under power compacts. 
> I'm in Pittsburgh, so if I went that route, would they
> require supplimental light (especially in the winter
> months? I'm in Pittsburgh)?    

They will definitely do better with supplemental lighting.  Most 
tropical plants do have a drier season so they can handle being in the 
house pretty well, but they still need a good light source.

Later,
Bill Wells


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