Who uses artificial light???

[JPB]

I am moving my plants to a greenhouse with not too much daylight. I consider supplementary lighting. What are you using and how does it work best?

Any info is welcome.

Thanks, Hans

[Anthony Darby]

To mimic daylight you have to have a large number of lights.

[JPB]

Yep, I know, but 100-200 umol.m-2.s-1 PAR will be enough...

[Anthony Darby]

I can't afford that kind of luxury.

[JPB]

Luxury or not.... That's one of the reasons why I'm asking...

[Carlo]

Hans,
I grow a wide variety of things under flourescent lights and high pressure sodium. As for "working best" it depends on a combination of factors...especially what it is you'd like to grow and what sort of lights you're using. For starters, most people keep their plants too far away from the light source. Many rock garden plants will be too warm under lights and it's difficult to get enough light to prevent them from etiolating.

[JPB]

Carlo, it is mainly to provide PAR during winter. Like Conophytum, young plants of Canarian/Mediterranean species and for sowing in early spring. So not extreme high light-levels. Most go outside during summer. I used Osram Biolux fluorescent lamps, but I'm wondring if there are better options.

Carlo, which type/brand of fluorescent lamps do you use? Do you measure photon flux density? High Pressure Sodium will be to costly, I'm afraid...

[Carlo]

Hans,

For my birds I use Phillips flourescents with a CR value of 93 or 94 (which I understand is as close as they will come to natural light). This is so that the colors show as true as possible.

For the plants, I must confess that I do not measure the light, nor am I overly fussy about it (probably to my detriment). I have banks of bulbs ready to be replaced...a January project. The plants are under the lamps full-time as there are too many to be put outside and brought back in--although some make the trip.

The main advantage to the HP lamps is working distance. They can be set at the ceiling and you don't need near as many to provide the same levels of light. The plants (mostly orchids under those) appear to love the light and do very well.

[jomowi]

I use warm-white fluorescent tubes for Gesneriads and Shortias, these require much less light than full sun plants where the organisation of the chloroplasts differs from that of shade plants.  It is also important to get a spread of the light spectrum rather than just a few spectral lines.  The photosynthetic light capture antenae work better that way.  High pressure sodium, Mercury or Blended (ballastless) lamps tend to run very hot and cannot be placed close to the plants, they will also overheat an enclosed space such as a growth room unless cooling is provided.  It can also help to place any ballasts or chokes away from the growing area if heat is a problem.

Brian Wilson

[JPB]

I plan to put the lamps rather close to the plants, so fluorescent lamps are the best (and cheapest) option.
But several companies advertise with "plant" or "daylight" fluorescent lamps, but I have no way to compare them, or their spectra or their output, in order to find the ones most suited for my plants...

Brian, is there a particular reason you use warm-white instead of cool-white? Maybe because those gesneriads have pigments to catch the green wavelengths on the forest floor? Which brand are you using? Distance? And do you have a way to estimate the actual irradiance (PAR) on the plants?

[Carlo]

Everything I've read says that cool white does just as good a job as any of the "special" plant lights for flourescent fixtures.

[johnw]

Everything I've read says that cool white does just as good a job as any of the "special" plant lights for flourescent fixtures.

Carlo  - I used to use Grolux but they got too expensive. I switched to 1 cool white and 1 warm night to get the full spectrum.  Cool whites - 48" - got very cheap about 10 years ago so now we use them only with no noticeable difference. On special they cost about $1 Canadian each and even less if you buy a case. As we use 22 bulbs it was getting too costly. Then there are 2 sodium halides in the coach house, we bought a propane furnace for the area but it rarely comes on due to the heat from the sodiums by day. In summer that area is well-ventilated so over-heating is not an issue.

johnw   - +1c & rain tomorrow, -17 tomorrow night. Bracing ourselves.

[Anthony Darby]

I notice that Tesco are selling the bayonet-fitting 12W and 20W (incandescent replacements) @ 5 for 40p!

[Maggi Young]

I notice that Tesco are selling the bayonet-fitting 12W and 20W (incandescent replacements) @ 5 for 40p!

Hmm.... a digression to domestic lighting.....

 Are those the "energy saving" type, Anthony? 
I understand that  very soon the standard 100w bulb will be withdrawn from sale in the UK, followed some time later by the withdrawal of the 60watt bulb...... speaking for myself I find all these "energy-saving" bulbs to be a waste of space.... I cannot see by their light to do any close work and they take too long to power up to light a staricase properly.... I heard on the radio the other day that new varieties are available which give more light, quicker.... but since the ones we already have are supposed to last umpteen years, it would hardly be a saving of either energy or money if I were to ditch the grotty ones now for the "improved" versions!!

Progress, it's a wonderful thing. 

Just hope the plants can see to read under THEIR lights!

[jomowi]

Hans, I use warm whites because they have a little more red to help the photosystems, but any tube will do.  Warm whites are not easy to get so often it is just white.  I would avoid the colder tubes as the red is much lower.  I also avoid Grolux tubes, they are expensive and offer few advantages.  I have never bothered to measure the light levels but the tube is about 15 cm-25 cm depending on the size of the plant from the plants.  In my research before I retired we used to make up large banks of tubes  say 120 cm square with the tubes ( 80w) at 80-100 mm centres spaced up to 60 cm from the subject.  Tube manufacturers will tell you the output characteristics of their tubes

Hope this helps.

Brian Wilson