Consequences of T8 lighting

[chopster01]

Currently I grow some Phals and Paphs in east windows and under 4 T12 light setups. My strap-leaf (non-mottled) Paphs don't bloom, so I have decided to change my four T12 setups to four T8 setups.

How much of an improvement will this be? Will my strap-leaf Paphs bloom under T8s? Would a multi-floral Paph? How about Bulbophyllums (I really like some of them) or any other medium light orchids?

Would the amount of added light actually be harmful to my lower-light plants in any way?

Is it really true there aren't any good T8 shoplights out there and that most die in a year or less (a nasty rumor I heard). I know T5s and other HO lighting might be better in some ways, but right now this upgrade is all I can afford. I seem to like low to medium light orchids best anyway, but there are always those handful of others...

Thanks for any help you can give me.

[John]

I grow under T8's and have been able to get Catts, Paphs, and Phals to bloom. I would use 4 tube fixtures with electronic ballasts. The lights can be just above the leaves but watch for flower spikes that will try to grow into the fixtures. When you change, watch the color of the leaves closely for changes in color that would indicate the lights are too close.
John

[mayres]

I doubt you are going to gain much by switching to T8. Better to consider T5. You should be able to bloom your phals and paphs with T12 fine - the trick is that you need them as close to the tubes as possible - literally. Also the strap-leaf paphs need (at least some of the complex types do) the seasonal lighting changes to be induced to bloom - so you need to consider varying your light length similar to outdoors - which will be different for your phals - which I basically give 16 hours per day year round and they love it.

[Ross]

Actually t8 lights are not a bad interim alternative. I know John grows under them as do lots of others. You just have to place them closer. T8's have much more light output than t12 and you should soon see a difference. I agree t5 are the ultimate (in florescent, anyways) but are much more expensive. By the way, you cannot just switch bulbs. You need new fixtures as well - the ballast is different. Even at Home Depot, you get what you pay for. Don't go for the cheapest. The ballasts don't hold up and light output from a shoddy reflector is not as good. Go for the best you can afford. Do you have a hydroponics store anywhere nearby? They should be able to fix you up.

I agree that more light will help with blooming the green, strap-leaved Paphs. Mine are often in full sun besides the CF florescent (based on t5 technology.)

[kavanaru]

well.... I do manage to have my Phals and soem Epicats blooming under T8

However, the Cats are under T5...

[chopster01]

Thank you all for such quick, great, if sometimes contradictory, input. I realize that differences in your opinions may be because I need to give you a few more details.

The plants I grow now are mostly Paphs and Phals and one Encyclia. The other plants I’d like to grow are Bulbos, Oncidiums, Phrags, and some Vandas.

I have two small east windows that are getting pretty crowded and two shelf areas where the lighting is used. The shelves in question are non-adjustable wooden shelves and the area I want to light on each shelf is about 4 ft X 16 in. Total clearance is about 22 inches between shelves. Currently humidity trays and the shoplights themselves take up about 9 inches, cutting clearance to about 13 inches, and naturally the plants themselves would fill that clearance a great deal. Of course I can adjust the height of T12 and T8 shop lights to get closer to plants if need be, but I can’t get any farther away than probably 1-8 inches from the tops of leaves, depending on the size of the plant.

If I did some more investigating into getting a T5 setup, as some of you suggest I should, my question would be: How far away do the tops of plants need to be from a T5 setup, especially low-light plants? Would low-light plants like Paphs and Phals actually be safe only 1-8 inches from a T5 set up?

Also, given the shelf area described above, would I be looking for a 2-bulb T5 configuration, a 3-bulb T5 configuration, or a 4-bulb configuration? (I am using a 4-bulb T12 configuration now and would also be using a 4-bulb configuration if I switched to T8s.)

If low-light plants could be safe 1-8 inches from a T5 bank of lights, certainly a T5 setup would give me more flexibility to grow other types of orchids as well, but that seems too good to be true and I don’t want to jeopardize the plants I already have.

The way I am figuring it, switching to a T8 setup would allow me to continue growing the plants I have, some of them perhaps more successfully, and maybe one or two medium light species I can’t grow in my east windows or under T12s--plus I would significantly save in energy costs over my T12 setup. A T5 setup in the same shelving configuration might be harmful to my low-light plants, though it would expand my capacity to grow higher-light varieties. Energy consumption with a T5 would be greater than with a T8 setup.

Please let me know how I might be misunderstanding things and if you would change your advice based on this info.

Again, I’m so grateful you are willing to take the time to help me think this through.

Thanks,
Charlie

[SheilaJ]

I found that the four-fixture, high-output T5 was too bright for my phals and most of my minicatts, and they were farther away than 1 to 8 inches.

Maybe you could do a mix of fixtures, use the low light ones for the phals and the higher light ones for the others?

[Oscarman]

My thoughts are 2 tubes T5 for a 16" wide shelf.

I have some mini Catts under 2 T12's and added 1 T5. The plants are about 3" away from the bulbs and they started to display some reddish/purple color change in the leaf margins indicating the lights getting a bit too bright.

Right now I have a 3' x 2' wide with 2 T5's that I am going to use for paphs and phals. The plants will be 4-6" away from the bulbs. A friend grows his Paphs and mini Catts 6-8" away from 3 T5's and has not trouble blooming either. His grow space is 24" wide.

I don't think the wattage of the T5's from Home Depot are as high as the ones from the hydroponics stores.