T5 or T5HO's or T8's

[PitcherASAMD]

Hey Guys,

I'm looking into building a set of light fixtures on a shelf for my orchids. Hubby is helping.
I grow mostly phals but have oncidiums, catts, a MAXILLARIA, paphs, haraella, miltonopsis, dendrobium and a few other random guys in the bunch.
1. How many lumen's of output do we need for these plants? Or how many candellas do the plants need?
2. Which is better to use: T5 or T5HO's or T8's?
We were originally looking at using T5HO's but are now questioning that decision.
3. Third question is which color temperature do we use? We have two options to go with: 1- put all lamps in 5000K using all the same bulb? 2- Or do a 50/50 split of 3000K and 6500K bulbs.
The overall question is which of those is a better plan? 4. We wanted to use a 4'x4bulb fixture. How far away should the lamp be situated above the orchids?

Any help would be greatly appreciated!
Thanks!
Katie

[billc]

Hi Katie, I grow phals, paphs, oncidium & harella fairly sucessfully under T12's & T8's in an unheated basement. I've used T12's for over 20 years and over the last 3 or 4 years started using the T8's.
To answer your questions:
1- There are a slew of websites that you can search and can get footcandle readings.
2- T5HO would be the best if you can afford them. They give great light and you can always move the plants wanting less light further away. I'm seriuosly considering buying a 4 light bank next time FirstRay's has a sale. Then maybe I could get catt's to bloom.
3- Reading thru the lighting forum, the general consenus is to use the 50/50 split. I try to keep the phals about 5-6 inches from the bulbs. The paphs at about 4 inches. The oncidiums I have under angled 2 light banks to get better coverage to all the leaves. They grow right into the bubls if I don't watch them.

Good luck, Bill

[Ray]

I won't claim to be an expert, but when I started carrying T5 fixtures I did some Googling, and while the consensus does seem to be 5000K, the spectral output of the 6400K bulbs is actually closer to that of sunlight. Maybe that was just the particular bulbs I was looking at...

In terms of light level per dollar, T5's are superior to the larger-diameter ones.

Katie, I am a discount distributor of Hydrofarm products, so if you want to take a look at their website, and you see something you might be interested in, I'll be happy to give you a quote for comparison.

[quiltergal]

I've been using T5s for about 3 years now. I'm only using the 6400K bulbs and have been successful at blooming everything but one stubborn bulbo. The 6400s are less expensive that the 3000-5000K, and because they imitate natural sunlight I think the color of the plants and flowers look more pleasing to my eye. I have had absolutely no trouble blooming catts with 6400s. Just my .

[silken]

I help with ordering orchid supplies for our local orchid society. We needed T5 bulbs last year as many of our society use T5's. I did much searching on the net to find out what is true 'full spectrum' and there doesn't seem to be a real black and white answer. In the end I bought 6400K bulbs which are considered pretty much the closest to full spectrum. Below is a quote from something I found. C.R.I.has to be considered too for lighting:

The term FULL SPECTRUM LIGHTING has no agreed upon standard or definition in the lighting industry. Instead, products labeled or sold as FULL SPECTRUM LIGHTING need only meet the definitions established by the manufacturer of the lamps or the vendor selling the lamps. In determining what products are sold as full spectrum lighting two criteria are most often considered, the C.R.I. rating and the color temperature rating (measured in degrees Kelvin).
C.R.I. stands for color rendering index. The color rendering index ranges from 1-100, with the higher numbers approaching the color replicating properties of full spectrum sunlight (sunlight having a C.R.I. rating of 100). Thus, the higher the C.R.I. the truer colors appear.

A C.R.I. rating of 80 or higher and a Kelvin of 5000 or higher is considered full spectrum.

Hope that helps. We really like the T5 fixtures as they are small, easy to retrofit into your old fluorescent fixtures if you had them and supposedly use less energy.

[PitcherASAMD]

Thanks to everyone for the wonderful and timely feedback! I'm definitely going with T5's and the 6500K spectrum lights. Now to figure out the least expensive route (as hubby can do electrical work) and finalize the size of shelves and thus bulb length

I'll keep you in the loop
Katie

[Pete]

I've been growing phals under t-5's 6400K lighting for six months or so. The plants are growing very well, but I am concerned that I do not have the optimal color spectrum for spike induction and flowering. All the literature that I have read says 6400K is for vegetative growth whereas the "warm" spectrum of 3000k promotes flowering. It is good to hear that some have had good success with all 6400K lamps. That said, is it optimal to mix the 6400 and 3000K to get a wider spectrum of light?

[RJSquirrel]

I understand quite often from what I have been reading many do mix the lamps of different spectrums together..I only use the 3000k over my wannabee bloomers as the windows provide the FULL spectrum otherwise...Winter might promote some 6400ks into the mix...My light is weak already inside this year so might be soon

[quiltergal]

I had to come back and say when I was watering this morning I noticed Mr. Stubborn Bulbo has finally kicked out a spike. So everything in my 83 plant collection that is mature enough to bloom has and does so regularly. Start with the 6400k and if you're successful there's no need to spend more on the others.

[RJSquirrel]

I notice that the CRI for higher Kelvin light is somewhat lower than the CRI for the 3000k and 5000k. 82 vs 85

I found some lights in the 6500k range with a CRI of 95...hmm all depends on whose testing these lamps

Also I read that Flourescent doesnt have the "penetration" that HID and MH have. ??? hmmm