Is it a wire shelf, or some other type? I ask because it helps to know what you have to work with as far as hanging lights off that shelf.

How tall is the shelf, and how much space between shelves? How many shelves do you want to fit with lights?

Also is there a reason you are limited to a 3' wide shelf as opposed to a 4' wide shelf? Is it just the shelf you have, or is there a space limit - such that a wider shelf won't fit in the space you have?

To my knowledge there are no 3' fixtures, but there are 18" fixtures. You could mount them end to end. It would be more expensive than a single 4' fixture, however. The bulbs are also more expensive, you have fewer options as far as light output and color temperature, and they can be hard to find.

Zensojourner presented some good questions in the above post.

If you really require a 3ft.fixture, there are a few t5ho fixtures available on the market (although they would probably have to be ordered online). Depending on your budget, one example would be the Sunblaster F39T5-HO one-lamp fixture without reflector (prices vary - around the ballpark price of approx. $25 without shipping). This fixture has a fairly good "optional" reflector that is easy to install.

As stated above, it really depends on the flexibility of your shelve unit (e.g., mounting and positioning options). If there was some way to mount a 4ft. fixture (creative engineering) over your 3ft. shelves, you could easily go with t8 fixtures. In regards to your question about other fourms... there is a vast array of knowledge & experience (compiled over the course of many years) on this forum. So much in fact, that it often takes a great deal of time to search and read through all the information. You had mentioned orchids in your original post. You could always Google orchid forums (and/or other specific plant forums). Most will usually have a lighting catagory/thread ~ might help give you an idea as to what (and how) others are artificially lighting their plants, along with maybe answering some of your questions.

Edited this post ~ for what its worth ~ to add a note about the above mentioned fixture: it includes a 6500k bulb .

This post was edited by o2tiller on Thu, Oct 9, 14 at 22:01

You can easily hang a 4' fixture off a 3' wire shelf. If there is the space for the fixture to stick out 6" either end.

Any other kind of shelf might require some creative engineering. Pictures would help ...

thank you zensojourner and 02tiller for your replies and info.the metal shelf unit was bought as HD,is wire ,about 55" tall.there really isn't room for a larger unit,it's in a plant room sharing space with baker's racks,tables etc with plants everywhere.even if i bought a larger size,there's no place to put this one. as for buying a 4' fixture i guess i could do that,but what about the 6" space on each side?won't that be a lot of wasted light?since my last post i have been readiing here and there is so much info here!thank you again and if you have any more tips please send them my way.

hi,also forgot to mention that the shelves can be moed up or down so lights should fit okay.

Its not really wasted light as the light drops off at the ends anyway. But here's the thing - a 4' fixture is a LOT cheaper than any of your other options.

But if you don't have room to let the light stick out 6" on either side, then I think you're pretty much stuck with trying to hang 18" fixtures end to end, or spending the mondo big bucks for the 36" fixture mentioned above.

The problem is that 36" is a non-standard size, and the 18" fixtures are nearly all intended as under-the-cabinet lights so - they're supposed to be screwed to the bottom of a cabinet and they nearly all have only 1 bulb.

You need at least 4 bulbs IMO to start seeds AND nurture them until they can go out into the garden. You can start seeds with just 2 bulbs but its just not as good for their later growth as 4 tubes would be.

To get that in the 36" fixture mentioned above, you're looking at a minimum of $64 per shelf for the (IMO substandard) 2 bulb setup, or $128 per shelf to get 4 bulbs up - assuming they will fit in the 11" or so of space that you have between posts. It looks like they will - but that's without any reflector, and you'll need reflectors for the 2 fixture option at the very least. I have no idea where to find the "optional reflector kit" or how much it might cost.

T5 high output light is supposed to be "better" than the T8s, but the difference seems to be somewhat marginal. I may be thinking of the comparison to overdriven T8 ballasts though.

At any rate. It will be less than half the expense if you can use 4' long T8 fixtures.

hello zensojourner,appreciate the info and comments.i just came back from HD,just to get an estimate on costs and what is out there.they have all kinds of the t types.i was more confuses with all the different fixtures tho.the 3' t5 fixtures are expensive as you mentiond.however,do i need 4 bulbs per shelf? i will be growing african violets on one shelf,phal orchids on another and perhaps either begonias or succulents.what do you think for each shelf?thanks you so much for your help!

Lighting is an extremely complex topic, and can be very difficult to explain/support. When you ask someone how a 25watt bulb compares to a 100watt bulb, the usual response is that a 100w bulb looks much brighter. This is a part of the complexity... watts is not a measurement of light, its a measurement of power. The lighting industry typically measures light output in lumens because most lighting companies are concerned with humans, not plants.

One definition of lumen puts this into perspective: a measure of the power of light by the human eye. Lumens can be very deceptive and misleading when applied to growing plants. A better way to evaluate light output for plants is to know the type of light needed to support photosynthesis in plant life. Photosynthetically Active Radiation, known as PAR (wavelengths of the light spectrum useful to plants, usually measured by PPF & PPFD - a measure of light photons) comes into play here.

{{gwi:1029755}}

{{gwi:1029757}}

Why use multiple fixtures and bulbs, when using one properly designed fixture (using a lamp that has a spectral output curve closely matching a plant's light absorption curve) will do the same thing? Would that one fixture grow 40 healthy plants in an 8ft x 8ft area? I seriously doubt it. Would it grow a few healthy plants on a 36" x 13" shelve? Sure it would.

Light output, efficiency, and efficacy, can become confusing. More power, more output, right? Not exactly. Using just one LED with a diameter of approx. 1.5 inches (e.g., Bridgelux BXRC-50G4000-F-04, 5000k with a CRI of 90) can output approx. 3700 lumens @ 31w, 4750 lumens @ 43w, and 6800 lumens @ 66w.

A typical 4ft t8 lamp runs at 32 watts and a typical 4ft t5ho lamp runs at 54 watts. If memory serves me correct (depending on the CCT & CRI of the lamp), a typical 4ft t8 lamp outputs around 2800 lumens and a typical 4ft t5ho
lamp outputs around 5000 lumens. The t5ho lamp has a higher lumen to watts ratio and a higher efficacy (not a misspelling of efficiency), providing more overall light when compared with a t8 lamp of the same length.

All in all... your choice of fixtures & bulbs should be based on what you can afford (cost of fixtures & bulbs - and cost of energy consumption), your particular application (type, quantity, requirements of the plants you grow), and cosmetic appearance (don't care because it's down in the basement, do care because it's in my livingroom).

Taking this into consideration: the quality of the fixture's ballast, the addition of reflectors (good reflectors on a fluorescent can increase the distribution of usable light to the plant by up to 30%), the spectrum of the bulb, the phosphors used in the bulb, and the diameter of the bulb (a smaller diameter reduces restrike) - a well designed fixture can provide a lot of light output.

Edit: added links for reflector & hanger in posts below

Here is a link that might be useful:

This post was edited by o2tiller on Sat, Oct 11, 14 at 21:02

Link did not appear, so I'll try again.

Here is a link that might be useful: ,a href=

And another link.

Here is a link that might be useful: ,a href=

Yeah, I'm not sold on the whole LED thing. There are too many issues revolving around spectrum and longevity and initial expense.

Not to mention canopy penetration, which is poor for any artificial light and I've never seen anything to suggest it was any better for LED lights. Those LED lights are tiny and you need a bunch of them to give good coverage.

There is only one "one light solution". It is called the Sun.

T5s vs T8s - the expense involved in a T5 setup is still significant, plus the T5s put out a lot more heat than the T8s, even when the T8 is overdriven. And it's a little misleading to point to the wattage of the bulb - you need to look at the ballast. An overdriven T8 will be running at about the same wattage as a T5, and will generate less heat. Depending on what bulb you started with, the lumens will be in the same ball park as well. I should get over 4k lumens from the cheap bulbs I'm using if I overdrive the ballasts.

Don't get me wrong, I'm not against T5 setups at all. But they do come with their own pros and cons and a big con right now continues to be the initial expense of the systems.

I'm still waffling over whether to go with T5s when I upgrade or overdriven T8s. The setup I am looking at is to grow tropical plants indoors, not just get some garden seeds started or grow some Basil over the winter. I have to take into consideration available amps as well as the initial expense. Operating expenses are negligible, for my setup, regardless of whether we're talking T5s, T8s, or LEDs.

But back to the OP.

I forgot you were growing orchids and African violets - I can't say about the orchids, especially since I'm pretty sure those vary pretty wildly depending on the exact KIND of orchid you are growing.

But African violets, in my experience, actually need more light than people usually think. I don't THINK 4 bulbs as listed above would be too much - but I'm also not sure 2 bulbs would be enough. It might be. That question I think would be better answered on the Orchid and African violet forums.

If they can tell you what your light needs actually are - then we can help you find the right equipment to do the job. It also matters how many plants and how much width you need to cover. Light falls off rapidly at all the edges of a light fixture, so - to fully cover those 13" wide shelves you still really ought to have 2 fixtures and 4 bulbs, unless you plan to restrict your plants to half the shelf, directly under the bulbs. You might also be able to go to a different spectrum - I just don't know what the needs in that regard are for African violets or orchids (or which orchids need what).

Maybe I'm wrong about that because everything I grow has fairly high light requirements - but I don't think even African violets will do well at the edges of a 2 bulb system over a 13" wide shelf.

Definitely hit it on the nailhead ~ nothing beats the sun.

For anyone with a Lux meter wanting to convert Lux to PPF, some simple conversion factors on the link listed below.

Here is a link that might be useful:

Not my night. I'll try that link again. If it does not take this time, conversion factors can be found @ www.apogeeinstruments.com/ppf-to-lux

Here is a link that might be useful:

hi 02tiller and zensojourner,thank you both for all the info.wow,there's alot to consider and digest!LOLi will need to read all this stuff a few times till it clicks with me and i understand more.i will post on the two forums and see what they say.then i will get back to you all.thanks again.

@ O2Tiller - yeah, I'm seriously thinking of moving to Florida ...

I grow african violets and phalaenopsis on an 18x48 shelf under a 4ft. 2 tube T8 fixture with one warm and one cool white bulb (2700k and 6500k). This is plenty of light to grow and bloom them, in fact last winter I moved the phals to the ends of the shelf where the light is less intense because they were turning red, phals bloomed this spring and the AVs haven't stopped. This is a simple setup that a lot of AV growers use with great results and you can't get a cheaper grow light.