Attractive, designed grow lights

[Pokey49]

There are more kinds of light bulbs than Carter has peanuts. I spent45 minutes studying light bulbs in Home Depot trying to find bulbs that would work for my orchids. Information was limited as everything was geared to home lighting use not for growing plants. There was bulbs described as daylight soft light warme light cool light etc. the term "full spectrum" was no where to be found. I finally went with a Philips incandescent Agro flood bulb for plants. 50 watts If that's not the best I can take them back.

[dolfanjack]

I have found day light cfl's to be the best. I grow carnivorous plants, citrus, and orchids and they all do fine with the day light bulbs. I also prefer the color of light they omit. Jack

[Pokey49]

So if I bought either a cfl Daylight 60/15 watt with > 3000K or a similar LED bulb that would work? Does the term "Daylight" = full spectrum??

[ALToronto]

Neither cfl nor led are full spectrum for any given colour temp. White light cfl (5000 K) are probably closest. I prefer mixing led's of different colour temperatures.

[naoki]

I did some measurement of light bulbs for another thread. 65W equivalent will give very minimum amount of light at 1 foot away. One of the decent performing bulbs (for plants) is Cree 18W LED Soft White (2700K) from HomeDepot (about $20). It is sold as 100W equivalent, but it gives light required for Paphs and Phals at 1' away (a bit lower than ideal, though) with a reflector. There is 5000K version, which gives the same amount of Photosynthetically Active Radiation (PAR) according to my measurement (I got 83 mircormoles/m^2/s from both bulbs at 1' away). However, in theory, red-shifted 2700K should be more useful for photosynthesis even these two give the same PAR.

[Pokey49]

This light stuff is also baffling. Does not seem there is any consensus on what is a good choice. I ended up, so far, with 9w/60w daylight LEDs with 5000k. The other choices I had at Home Depot were 50w flood Agro/grow lights but they got awfully hot. The only other available choice was 14w/60w cfl daylight. Of the three what do u think is the best choice?

Confused,
Pokey

[naoki]

Pokey, yes, it could be confusing because biology is complex. If you are interested, there are lots of good informations based on science (but don't trust everything on the web as you probably know).

I'm not sure what is 50w flood agro light. Is it a halogen based flood light or an LED flood? But if you compare the CFL vs LED, I would choose LED. However, there are quite a bit of variation among LED household bulbs. Anon Y Mouse has some comparison posted: Comparative Light Shopping Philips had the highest output in terms of footcandles, and Cree was pretty good, too (note the lower energy consumption). I believe Philips has high output toward the tip (so good for normal reflector), but cree has high output toward the side of the bulb (so good with side reflector). There are also several models of Philips, so you should be careful. The flat one from Philips is not so great according to my measurement (I don't have the model Anon Y Mouse used).

If your 9W 5000K LED is from Cree, I know it is a pretty good one (I used it and I have measured), and it has 10 year warranty. It is the smaller version of what I recommended. You have to place the plants really close (around 6" or less for Paph and Phals) or you need to use lots of them. This is true with small CFL bulbs, too.

But if your condition is far from optimum (e.g. extremely low relative humidity), you may not see much benefit of placing the light close to the plants. The optimum amount of light is environment dependent. In one study of Paph insigne, photosyntesis reached maximum around 100-200 micromoles/m^2/s (Williams et. al 1983 Plant Physiology 72:906-908). Their environment is pretty decent (good temp, good RH).

So Cree 18W from 12' (820 micromoles/m^2/s) is a little lower than the optimum, but it isn't too far off. If you use 9W Cree from 6', you should be getting about 1600 micromoles/m^2/s in theory, so it is a pretty good amount.

This is probably way more information that what you want. Efficiency differences which I'm talking about are probably not so important to some people, and in reality, you can grow orchids with many different light source.

[Pokey49]

Naoki. Yes my led bulbs are Cree 9w60w bulbs. I have them in a 5 headed/fixtures lamp. They are a 5000k bulb. I don't see any easy way to get the lights within 6 inches of all the plants as I have my orchids sitting at multiple tiers. It sounds like I have reasonably good set of led bulbs to work with. I will work the situation and see what happens. I am just wanting to supplement my lighting during these gray winter days. My orchids are I my sun room which has windows in the north east and west with sky lights so think my lighting is pretty good for the most part. I have paphs coming back in bloom and an Angraecum with a new spike forming. My Phals are what have me perplexed. They should be showing some spikes but for whatever reason are not. Everything else (water temps fertilizer humidity) the only I can come up with that they are not spiking is light. Will see what happens in the next couple months. Hoping the extra light is the cats meow.