"Rusty Hinge" wrote in message
...
The message
from "Janet & Tim Costidell"
contains these words:

Has anyone done this? My boss wants us (myself and colleague) to grow
tomatoes in the greenhouse for him over the winter. We have good
heating in
there, and sodium lighting. Has anyone attempted this before, if so,
how do
we do it?
/\
Hmmm. Somewhere / \ up there I answered a similar query.
¯||¯
To get good results you have to fool the plants into a belief that it is
summer. The lighting should be daylight bulbs, I don't think sodium
light would be suitable.

Sodium light is totally ineffective for promoting photosynthesis. Mercury
light has a couple of lines in the spectral regions involved in this
process. A "High pressure Sodium lamp" contains a drop of Mercury. This is
what gives it the characteristic blue colour which swamps the yellow of the
Sodium doublet after the lamp has warmed up.

Franz