Hi there, I am a fellow noob myself. I just started my lighting project using the same shelving you have pictured except for my personal needs I disassembled it and essentially hung it from the ceiling, with each shelf being hung from the previous unit with chain.

Now, hanging it is completely unncessary in most cases, your stand up unit will work just fine as it is with the light fixtures hung underneath the shelves. However, I realized one thing in the process about the lights. I bought my light fixtures from Walmart, they are cheapo light duty T8 two-bulb fixtures. They are 4' long and about 8" wide at their base and this is probably standard for this price range. You will have no problem at all hanging one fixture per tier but you might run in to trouble if you want to hang two fixtures side by side. You'll have to measure the depth of your shelving between the support legs, not to the outside edge of the shelves. You may not be able to squeeze 2 light fixtures between those legs unless one of them is turned slightly upward and not straight down which makes it less effective.

You may not even need more than one fixture per shelf for what you're doing, but if you planned to then you'll have to take the width of the ballasts into account and make sure they'll fit between those legs, perhaps you can find narrower 2-bulb ballasts or maybe there are 4-bulb units that will accomodate that measurement, whatever it is. The 4' long ballasts are certainly longer than your 45" long shelves so whatever you buy in any combination they will have to fit between those legs.

I hope this is making sense?

Because my shelving was hung with chain and not fixed with a rigid leg I had a little flexibility, there's some give with chain so I was able to squeeze two fixtures between them, but just barely.

As to the kind of fixture/bulbs you choose I'm sure lots of folks will weigh in, there are many threads on this subject. The general advice I took after pouring over them was to go with a T8 fixture rather than T12 because they are more efficient although the bulbs can be pricier but not exorbitantly so. The bulbs will last years in most cases so that's not exactly what I consider a recurring expense. The other advice I took was not to mess with the "one cool white, one warm thing" or specialized grow lights and I just went with bulbs that were labeled "daylight". There are all kinds, "neutral", "kitchen/bath", etc....and I had a little trouble finding T8 "daylight" at my Lowes but they did have them. I paid $8 for a two-pack, don't know if that's good but that was my only option. Bulk will be cheaper but again, how often will you be replacing these bulbs? I didn't need 30 of them right now. I have read many many threads about lumens, penetration, overdriving, light spectrums, etc...until I was cross-eyed. I understand some but not all. In the end, I went with something simple that seems very effective for alot of people.

Good luck with your project. My thread with pics is a recent one too, I linked it below. That chrome shelf that's hanging is identical to yours, I had just spray painted it black because it was so rusty from being outdoors. I'm going to hang the other chrome shelves below that one as it progresses.

Danielle

Here is a link that might be useful: Chrome shelving hung

Danielle,
Your post made perfect sense and was very helpful; thank you for taking the time to write it! I had not realized that I could get a fixture longer than 45", if I had to, as long as I get something that fits between the vertical supports.

Do you happen to know if I'll run into any problems, since my plants are all different heights? Will a light that is too close to my taller plants cause any sort of "burn?"

My understanding about about the fixtures is that they are typically 2 feet long, 4 feet long (most common) or big ole' 8 footers. One interesting thing is that often a 4 foot fixture is cheaper than 2 foot fixtures, I guess there just isn't as much demand for the smaller ones. My fixtures were advertised as 4' and they are exactly 48 1/8" inch so that was basically accurate. The standard bulbs themselves are just under 48" long so the fixture has to be at least that long, maybe longer depending on the design. There are also smaller more unique fixtures with different sizes and shapes of bulb, not just the plain old rectangular ceiling kind, but the large standard square fixtures will probably give you the best coverage for your shelving.

I am just starting myself, haven't even planted my first seeds yet so keep in mind you're talking to someone else who is basically at the same place as you are lol. I'm hoping to plant my first seeds tomorrow, just need to get some bottom trays for the flats. The general concensus I read about light placement was about 3 inches from the top of your plants. If you have some varieties that are shorter than others you can actually hang the light unevenly....the chain on one side longer than the other and place them on the rack so that they graduate in height to the other end. Or, if you have multiple tiers, try to arrange things of similar height on one shelf, taller or faster-growing items on their own level, etc....You'll probably have to figure these out and adjust as you go along.

Looking at a sloping light is probably going to really bug my "everything must be level" sensibilities lol so I'm going to try to use different tiers to accomplish the varying heights. But I have a feeling the plants will ultimately dictate their terms to me so we'll see how that works out lol.