Do you have window light? You need to give more info. such as what type of orchids you are growing. The light is strong now outdoors and if you have window light you should be able to flower your plants with the lower bulbs. If they are already budding, you should be fine for two weeks.

Tell us what you are growing.

Jane

Actually, I found a 23W, so the initiating reason for the question is moot. BUT, just for reference, I still am interested in the answer to the question: are 2 lower watt CFLs as good as 1 higher watt CFL, or is the higher watt CFL always better? To further clarify the conditions of the question, no, there is no window light available to the plants under lights (window space has been claimed by other plants). If it matters what is growing under the lights, here's the list: phal equestris, phal stuartiana, jasmine Maid of Orleans, jasmine Grand Duke of Tuscany, NOID yellow phal, aerangis citrata, two African violets, osmanthus fragrans. Yes, not all of them are orchids : ) And no, these are not all growing under the same lights... the jasmines and phal stuartiana are under the 23W, the same phal stuartiana is under spillover from the 13W the phal equestris is under, and the rest are under a different 13W tube.

Thanks!

I'm not sure if 13W is enough for those phals, but it'd be interesting to see whether it is. I don't think the difference between 2 13W and 1 23W is significant in terms of plant growth. I hear that with these lights, the higher intensity is there simply because with the huge blasting of lumens, some of the needed wavelengths can be covered. Unless your plants are within inches of the lights, with the amount of drop-off, a 13W and a 23W will be comparable at 1 ft distance.

Theoretically, you would get a larger area of slightly less light with 2 lower wattage lamps compared to 1 higher wattage lamp.

So, it wouldn't make much of a difference if I had 2 13W bulbs? If not, I won't bother putting the 2nd 13W tube up on the same shelf; instead, I'll put it up on a new shelf and have two shelves with lights. The phal equestris is under a 13W, about 3-4 inches away, and it's bloomed twice and is putting out new growth. In fact, its leaves are turning purplish. Phal stuartiana is about 4-5 inches away from the 13W, and about 8 inches away from the 23W, and is putting out a lot of new growth; it even has a speckled leaf now, when it looked to be an all green variety (so, it probably wasn't an all green variety after all.) I don't know whether or not it makes a difference that the 13W the phal equestris is under is an Ott-Lite? (Ott-Lites are used in crafting where color matching is important, because it imitates daylight). It is getting a bit of spilloff from the 23W, but not a whole lot, because the 23W is facing away from it, and it is about a ft away from the light to begin with.

So, it appears that these phals are happy. The jasmines are definitely happy, and they are high light, full sun plants. You can maintain them under lower lights, but you can't bloom them without enough light, and one is blooming like mad right now, and both are putting out a LOT of new growth. I feel like I must be doing something right, with those results.

Anyway, it FEELS like having more lights should be better or comparable to one light, even if it's a higher wattage, but I haven't done the theoretical math/reasoning to decide whether that's true or not. If anyone has, please let me know! Because otherwise, I'm inclined to just invest the money in getting fewer but higher wattage bulbs.

Q,

It's my opinion that multiple lights are an advantage when dealing with multiple plants. You can adjust the lights for proper height much easier than adjusting the plants.
I also believe the old H (btw: Where has Howard been?, some nasty remarks must have chased him off along with Clara. Obviously people don't like to be told about proper light?) adage: More is better in almost all circumstances. When dealing with artificial light too much is hard to obtain. That said and if it's possible: I think you should go with all 23's... In checking the 'net, a 13 has @750 lumens, a 23 has @1600, significant difference.

Bob