Hi all,
Can anybody suggest a light source that may be likely to maintain this exasperating plant?
High-pressure sodium lamps still have the highest PAR efficiency (~1.5 µmol J-1), but they run very hot, and the fixtures and bulbs are quite expensive (sorry just saw Marcel's post, what I should have said is that I agree with him). They also show relatively fast lamp lumen deprecation.
LED's are probably a better option and if you didn't want to invest in a Kessil etc., you could try something like a 6500K 50W LED "Floodlight" placed over the plant, probably on a 14 -16 hour day.
If you don't mind the colour rendition a red/blue or blue grow light would be the best option, and they would give
you more PAR per watt. "Blue only" would be the most efficient for vegetative growth.
Kessil sell a "blue" lamp (
A160 WE Tuna Blue LED Light), or there is a "Tomato growing" LED like a <"
PlatinumLED">. I haven't looked, but on "grow your own" forums there will be a lot of information about which LEDs produce most PAR, last well etc.
An array of 3W LEDs is thought to be more efficient than using 1W or 5W LEDs, but I don't know how this compares COB LEDs, my suspicion would that COB LEDs will soon be the light of choice reasonably soon.
There is a review here <
"Light emitting diodes in Horticulture">.
cheers Darrel