Peter's 20-20-20 is not a good fertilizer for hydroponics. It has too
much ammonium nitrogen, which drives the solution pH down, and lacks
calcium. Your plants probably had a severe calcium deficiency.
Use a half strength Hoagland solution or commercial hydroponic
fertilizer that contains all the essential elements. Peter's Hydro Sol
(5-11-26) is designed for hydroponics and has 100% N as nitrate. It
requires that calcium nitrate be added because Hydro Sol also lacks
calcium.
http://www.scottsprohort.com/_do***ents/WSF/PetersProfessional/H4032.pdf
You could probably cut the nitrogen to 100 mg/L. A cheap pocket
electrical conductivity (EC) meter can be used to monitor solution
depletion.
David R. Hershey
On Aug 27, 6:19 pm, "Cote, Gary G" <gc...@[EMAIL PROTECTED]
> wrote:
> Plant Ed folks,
>
> Has anyone grown Pistia stratiotes (water lettuce) for research or
teaching? If so could you share any tips? The papers I've found in the
literature mostly say they grow it in Peter's Professional Fertilizer
20:20:20 in the greenhouse in plastic tubs. I've got them in black
plastic tubs in 20 L of water containing 0.325 g Peter's 20:20:20 per L.
I tried 0.5 g per L. I've been using nanopure water to avoid chlorine and
other trace contaminants, although I had expected to switch to tap plus
Peter's when they were growing OK. Temperature is 22 by night, 26 by day,
colder earlier because I had problems with the growth chamber temperature.
They get 14 hours light and 10 dark. Water is changed weekly or every
other week (because of travel). They did poorly at first, and several
died. Then I had one week the survivors started looking really good and
produced a lot of offshoots. Then I went away and they got a cold shock
when the power failed (4 C, I'm told). They don't seem to want to
recover. The leaves are rotting, and the "stem" will just collapse in a
froth of bubbles. I've got one or two originals left and a few surviving
offsets. Any suggestions gratefully received.
>
> Gary
>
> Gary G. Coté
>
> Department of Biology
>
> Box 6931
>
> Radford University
>
> Radford, VA 24142-6931
>
> (540) 831-5630
>
> (540) 831-5129 fax
>
> gc...@[EMAIL PROTECTED]
>
> http://gcote.asp.radford.edu
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