Alan wrote:
In message , Chris Hogg
wrote
On Tue, 15 Jan 2008 16:49:49 -0000, "Anthony"
wrote:

Hi
Can anyone tell me what lights/bulbs are used in the greehouse to
extend the growing hours for seeds. I have done a 'Google' and
there are a great many different bulbs out there, and they seem to
be mainly for growing plants for 'your own personal use'!!!
I would like to extend the growing hours for my veg seeds so they
are well established possibly for showing this year, fingers
crossed. TIA
Anthony

You need powerful lights. Most domestic stuff isn't up to it. See
http://www.twowests.co.uk/TwoWestsSi...W_GROLIGHT.htm



Wouldn't it depend on the distance between the plant and the light.?
In a commercial greenhouse you may use a powerful light to illuminate
a large area. In a small greenhouse, and possible for a smaller area,
couldn't a compromise be made with a lower power bulb placed closer to
the plants?

You can grow quite a lot of algae in a fish tank illuminated with only
40W of strip lights

Quite correct. If you wanted to cook seedlings, then a powerful lamp (250w)
placed close to them will do it nicely. This Gro-lux lamp is the sort of
thing you should be looking at:
http://www.lightbulbs-direct.com/var...l.asp?var=3704

Even then, they will add heat to a closed propagator. I use a 25w Gro-lux
and it pushes the temp up by around 10°C when placed directly on the
propagator lid (I put aluminium foil above it to act as a reflector - but of
course that just adds to the heating problem).

Hopefully, in the next couple of years we will see LEDs become available
which are more efficient than fluorescent lamps (eg see
http://www.ultraleds.co.uk/cree-mr16...a2bd8d01c04ed2
for something not too far off). Whether they will have a suitable spectrum
for plant growth is another matter.

--
Jeff
(cut "thetape" to reply)