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Substrate depths

Karen wrote:
> Steve Pushak wrote:
> >During my recent move to the new house, I had to remove all my plants.
> >As you know, I use dirt in the substrate along with clay fertilizer
> >balls. The root mass of the plants was quite small except for Crypts
> >which had long rhizomes but small roots.
> >
> >This is because plants which are growth in infertile conditions have a
> >larger root to shoot ratio. Plants grown in more fertile conditions do
> >not invest as much growth energy into producing a large root system.
> That assumes that the plants are small.  Plants grown in infertile
> substrates may grow PROPORTIONATELY more/longer roots, but in general 
> big plants have more/longer roots than
> smaller ones.

Yes I would agree generally that the age of the plant (more important
than its size) will indicate a much larger root system. As plants grow,
the root systems also continue to grow. We (aquatic gardeners) sometimes
prune stem plants and trim leaves from crown plants but rarely do we cut
the roots. I think George says he regularly yanks up stem plants like
Bacopa and discards the old portion with the roots and replants the
tops. Instead of doing that, I sometimes pinch the stem off level with
the substrate and occasionally replant the tops leaving the roots to
either die or regenerate new stems.

I've never done it but I think you could also take a garden trowel and
chop down around some of the plants like Echinodorus amazonicus to limit
the root spread and kill some of the roots. 

After my recent move, I decided to take a leaf from Karen's book and use
pots to contain the spread of some of the more rampant Crypts. The 74
gallon cube tank is now done entirely using clay pots placed on multi
level clay bricks for a terraced design. The foliage is not very dense
yet but I like the look of it so far. I think a tank looks best for the
first year after it is set up. I don't like to disturb the plant roots
and Crypts are bad for invading. I'm hoping I'll get some really dense
growths of Crypts in the pots that stay confined.

>  It seems to me that it is still entirely possible for plants
> in a good nutritious substrate to completely fill their container with
> roots... Particularly if we continue to prune the top of the plant, and do
> nothing to trim the root system.  My house plants on the window sill,
> properly fertilized, with no access to nutrients anywhere BUT through their
> roots do this on a regular basis.

I had an E horemanii that was in the tank for a couple of years (as best
I can recall) and I was surprised that the roots were not more
extensive. It was a very large specimen and I'd had to trim the leaves
on a couple of occasions to prevent shading its smaller neighbours. I'd
avoided feeding this plant because I knew from past experience how huge
Swords can get. I'm sure it was getting _some_ nutrients from the small
Crypts nearby which I was feeding.

For comparison, I estimate the root ball of the E horemanii at about 6"
while the stems and leaves were about 20 - 24".

Steve Pushak                              Vancouver, BC, CANADA 

Visit "Steve's Aquatic Page"      http://home.infinet.net/teban/
 for LOTS of pics, tips and links for aquatic gardening!!!