"Arthur Suggitt" wrote in
:

When I plant bunches of Elodea & Cabomba with lead strips around the
bottom of the stalks the bottom 10cm start to rot.


Elodea densa and cabomba are both stem plants. The stems should be
separated from the bundle and planted individually. You can plant Elodea
(not cabomba) in small groups of two or three stems, but it will do best if
each stems is planted 7 - 8 cm apart. If you don't separate the stems from
the bundles the bottom leaves will not be able to photosynthesize properly
and will die and drop off.

Cabomba especially should only be planted as individual stems. I've found
cabomba will take forever to root properly in the substrate if the bottom
portion of the stem is not receiving enough light. If it gets enough light
once rooted, cabomba will branch like mad just under the substrate, and if
you've planted other stems too close together the new growth will quickly
starve everything of light. It is best to space the plant out and allow it
to fill out naturally.

BTW... if you're having problems getting cabomba to stay in the substrate
as widely spaced stems (they used to do a lot of floating and frustrate the
heck out of me until they finally rooted) you can actually plant cabomba
sideways to force it to stay put. Just plant a good portion of the plant
just under the soil in a horizontal fashion (weigh part of it down with
rocks if you like) the exposed part will quickly redirect itself towards
the light, and the buried part will drop loads of roots and sprout new
growth all along its length--provided it isn't buried too deeply.

Elodea doesn't seem to branch at the root like cabomba does, but it will
divide and fill out naturally as it grows--regular pruning of the growth
node(s) will encourage it to branch and fill out even more.

Both of these plants are very fast growers. I've seen cabomba grow 1" a
day quickly reaching more than 1 m in length. Make sure to prune regularly
to maintain uniform growth and to ensure one or two stems don't strangle
all the rest out.