How effective are basic fluorescent grow lights?

I’m building Mrs. Devil a gardening workstation in the basement to help take care of the 150 or so houseplants we have. Some need special care, whether from recent repotting, absent minded neglect, gravitational irregularity, or a child just learning about vivisection.

Given that this will be in the basement, it will need a lighting source (there’s the also been the question of what to do about a plant-ICU in the winter). I can build just about any type of bench, but Harbour Freight has a nice, inexpensive prefab bench that is just right for her. It has a built-in “22-1/2" long 13 Watt fluorescent cabinet light.”

There are all sorts of fluorescent grow lights out there (and I can always replace the included ballast), but are they worth it in a non-grow chamber situation? We’re not looking to grow the plants per se, just give them a week or two of close-to-summer-sun as possible. We’ve seen those countertop herb gardens , which seem to have fixtures similar to what we’re looking for, but have no idea if they work or are a gimmick.

This question has nothing to do with pot, but experience with indoor growing might be germane.



I’m puzzled about the reference to a week or two of summer sun-type lighting. Would this be to push certain plants into flowering? Or are you looking for longer term maintenance, for instance over the winter?

I have several plant stands in the basement using fluorescent lighting, and all of them have T8, T5 or T10 bulbs, either in four-tube fixtures or two double-tube fixtures. These use a mixture of cool white and warm white/daylight tubes, no special grow light tubes (which are of questionable value, especially for foliage plants, and tend to cost a mint).

LED lamps can really help boost lighting (and especially flowering), and are fairly thrifty from a power consumption standpoint. I use a couple of strategically placed UFO-type LED fixtures and those things really throw out strong lighting, which benefits even plants five feet away on the floor.

Do LED lights provide the broad spectrum needed for plants? I thought that they were very spiky in their output wavelengths.

You need to take care of the humidity too.

I’ve used a T5 fixture (4 bulbs) for years to start plants before spring and to help a few plants I keep year round. The year round plants are in a window but during the depths of winter I’ll put some of them under the light sometime, when I’m feeling nice or they look sad. Usually I’ll start plants for my summer garden under the light. Before that, I might plant a quick, small lettuce crop in a tray. That only takes a couple of weeks.

The bigger problem is controlling heat, humidity and bugs. Mites love the perfect conditions inside and can take over a small plant in days.

Oh, no interest in forcing flowering or anything like that. I mentioned ‘summer sun’ meaning to imply nice, strong light that will help them the most (as opposed to the timing or cycling). Our use is much more like shiftless’ use of starting plants or putting them under light when they seem to need it. We also take in a lot of ‘rescues’, those sad plants on the clearance rack that are barely clinging to life. Many of them do great after a while of careful attention. Our hope is that we’ll be able to bring them down to the bench and if repotting is not in the immediate cards we can leave them there under the lights until she gets around to it.
It sounds like either the T-5/8/10 lights will do fine–and am interested in the LEDs, particularly power savings-wise. Any particular type of LEDs?

I’ve noticed the mite issue myself – the plants that I bring in from the garden (and then neglect) tend to have a thick coating of the buggers by mid-winter. My question was, “What keeps the mites in check during the summer when the plants are outside?” I’m assuming that there are various wasps and beetles, but is that the whole answer?

I wish I knew what keeps mites in check. Lady bugs do the work, I hear, but I never see very many around the plants when their outside so who can say. Part of it is humidity. I think spritzing often can help. Some of our plants (hibiscus, I’m looking at you) can be crawling with the buggers by mid winter and I have to throw them out into the cold and/or spray with poison. I know mites won’t bother me but it’s just creepy to have all those millions of bugs writhing in the house.

IIRC, regular fluorescent tubes are pretty weak in terms of light. A 13 watt tube only puts out roughly as much light as a 60 watt bulb, which isn’t much relative to the sun.

When I tried starting seedlings using regular bulbs, they got pretty leggy and didn’t seem too healthy.

I got one of these in the 200w variety, put it close to them, and they did fine. The same setup also worked for keeping a potted lemon tree alive in the winter.

Daylight spectrum fluorescent tubes work great, especially if you mount a fixture to throw from the side, too. Adding a halogen flood to the mix helps, especially if you need to warm the area. Total ambient light is probably more important than full spectrum, a bright windowsill in your house is 1100 to 1500 footcandles by exposure meter so the closer you come to that the better. You want over 500 for tropical foliage…

How about daylight spectrum LED s?

I don’t claim to be an expert, but, from what I’ve been reading, you can use LEDs as growlights, but few people do for small scale gardening because there’s little advantage over CFLs, which are cheaper to purchase and if you’re only running them a few hours a day, 8,000 hours is years and years of life and most people can swing the $1/mo electricity cost ;).

The people who really seem to get deep into the debate between CFL and LED are people who run their growlights continuously. Other than a few super dedicated plant hobbyists (I saw this one guy who has a tropical forest in his basement in Queens), that group seems to be mainly pot growers, lol.

Also, to the OP, lots of things are labeled “Daylight” but check the label - you want light in the 5000-6500K spectrum.

Surely, it being winter in the northern hemisphere, you don’t want summer sun but winter sun?

We do the same… in the spring we grow vegetables from seeds indoors, and we use a four foot fluorescent fixture containing two “cool” cool bulbs and two “warm” color bulbs. Works great.

I don’t have a ton of experience with LED lamps (there are many kinds on the market accompanied by varying degrees of hype), but I’ve had good results with this lamp, which is relatively cheap. I use a couple of them in my growing area, mostly to augment light for citrus and other plants kept on the floor between fluorescent light stands (some plants are too tall to fit on the plant shelves). I have one additional LED lamp that only gets used at seed starting time for extra light (seedlings can get leggy under fluorescent light fixtures). You have to be careful not to blast seedlings with too much light, which can happen close up under LED fixtures.

But again, ordinary shop light fixtures with a mix of cool and warm white fluorescent tubes will be fine for growing most plants indoors, and even getting many (gesneriads, other tropicals) to flower. You can fix up a basic three-decker plant stand using utility shelving and shop lights for relatively little money ($100 or less).
Preventive bug spraying with a horticultural soap solution helps keep mite and whitefly populations down.

For the last two years, I’ve been doing seedlings, I did mostly fluorescents (just a normal work bench light in my workroom–no idea what the wattage is) with a mix of incandescent and my peppers and all grew fine and I ended up with more than I knew what to do with. I seem to recall reading somewhere that fluorescents alone can cause leginess because of the blue-green spectrum of light, and it needed to balanced out with the yellow of incandescents. No idea how true this is, but it worked well for me.