Shop lights?

Litchfield Park, AZ

Hi all, sorry about this question but I'm really wondering if I already have shop lights I would hate to go out and buy more. ( it has something to do with vegetables because I need to put my seedlings under them asap.) By the way one of them is a lamp the other one is a long ine screwed onto a work bench.

Thank you for your helo :)

Thumbnail by Sandra513 Thumbnail by Sandra513
Contra Costa County, CA(Zone 9b)

Fluorescent lights vary in what wavelengths they produce. Old light are very low light compared to what plants need, though they seem bright enough to our eyes. Our eyes see yellows and greens the best. Plants use certain wavelengths in the red and certain wavelengths in the blue areas of the spectrum. Most 'shop' lights will be rich in the wavelengths that we see best.

If you are going to move the seedlings out pretty much as soon as they sprout, then you are probably fine even with old lights. You really just need the light to see what you are doing, the plants won't be there long enough for it to be a problem.

But if you want to grow them on, get a bit bigger before transplanting them to the garden I would look into new bulbs.
If you can find some with a K value of about 6,500K, or that are labeled 'daylight' that will be better than old bulbs.

If you want to grow the plants even longer, then I would put in some money to get good reflectors and special bulbs that produce the right wavelengths for the plants. Do some research about the PAR rating system for light.

Litchfield Park, AZ

Thank you so much for the reply and explanation :). I'll definitely look into it

Everett, WA(Zone 8a)

If you replace the bulbs (a good idea every 2 years if you run them 18 hours every day), one "cool" bulb and one warm" bulb is an alternative to two "daylight" bulbs. They may be cheaper than "daylight" bulbs. Also, maybe but not certainly, more efficient.

If you do get around to buying new fixtures some day, either T-8 or T-5 fixtures are MUCH more efficient than old "T-12" bulbs. T-8 bulbs draw less power but as bright or a little brighter than the old T-12 bulbs.

T-5 bulbs typically draw more power, but they can be as much as twice as bright as old T-12s. And they are m ore expensive, but not twice as expensive, you they are cheaper per lumen.

Lumen measure the brightness. Watts measure how much electrical power they draw. The new T-8 and newer T-5 bulbs give more lumens per Watt than the old T-12 bulbs.

T-5 bulbs are still being improved. There are T-5s made that more more efficient, OR brighter, OR longer-lived. But prices are still higher per bulb (not always higher per lumen).

Liberty Hill, TX(Zone 8a)

When I use one warm bulb and one cool the seedlings seem to lean towards the cool lights so now to grow seedlings I use cool lights but if I want them to flower and produce I use warm bulbs.

When using shop lights keep your seedlings 1-2 inches from them. It may seem too close but it's not. : )

Litchfield Park, AZ

I was wondering about the distance, since my cucumber seedlings seem to be dry (not the true leaves) just the very tips I was afraid they might have too close. I guess they are not..these are the cool lights.

Thumbnail by Sandra513
Everett, WA(Zone 8a)

>> if I want them to flower and produce I use warm bulbs.

I've heard that from several sources.

Thanks for the tip about "two cool bulbs".

Litchfield Park, AZ

But if I'm only waiting until they get bigger to transplant then I'm ok with the cool lights right?

SE Houston (Hobby), TX(Zone 9a)


SE Houston (Hobby), TX(Zone 9a)

Cukes are what I call "water" veggies. They soak up a lot of water to produce a "water" filled veggie. Like a "water" melon, or a juicy tomato, or zucchini.

They might be a bit thirsty... how moist are you keeping them in the seedling tray?

Litchfield Park, AZ

Thank you, first garden :). I planted Green arrow shell peas and provider snap bush beans yesterday.. who knew getting the soil ready was so much work! I feel like I worked out yesterday.. very rewarding tho

Litchfield Park, AZ

I hadnt seen dry soil so havent water them I will today.. I was having mildew issues but havent seen those nasty webs since I put a fan on them ( not directly)

Litchfield Park, AZ

Okay so I lost two cucumber seedlings to root rot, i lifted the other ones to let air circulate under them a bit, the leaves are looking very dry now but cant water them *sigh* hope they don't die.

Everett, WA(Zone 8a)

I agree that you don't want to water something that's rotting.

Maybe you can wick some of the water out of the soil by setting the pots or cells on top of paper toweling on top of a terrycloth towel, old cotton socks or a Tee shirt. When you get the water out, air can enter in, and probably the roots need air.

When they are ready for more water, consider watering with dilute hydrogen peroxide. That should help a little at knocking down molds and fungus. Also, it carries a little oxygen into the soil and releases it where the roots need it.

maybe 0.2% ... dilute the 3% stuff you find in drugstores 16:1: like 3 tsp of peroxide per cup of water, or 2 ounces per quart.

Others have used it much stronger without killing seeds. Maybe it is safe to use it stronger on roots: yours do sound pretty sick.

Don't be upset about a setback! You've already achieved the first level of gardening success: they aren't ALL dead! I can remember (it was quite recent) when every seed in three big trays failed to emerge. And every seed in two big tubs (except for one species that came up months later) never emerged. Over-watering and waterlogged soil.

Did you say "first garden"? They sprouted AND not all the seedlings died. You're doing really well!

Everett, WA(Zone 8a)


Did you see this other thread? If those photos look like your plants, consider those suggestions.

- is it only the tips of the first pair of leaves (seed leaves or cotyledons) that turned brown? That is normal.

- Are you fertilizing baby seedlings? Don't. Or so it REALLY dilutely.

- if you water from above, try to avoid splashing onto the leaves.

"Leaf and tips on cucumbers seedlings are dry"

Litchfield Park, AZ

Thank you so much for the encouragement!! I will do that and keep you posted. I am LOVING the process even with the set backs :) I appreciate the help.

Everett, WA(Zone 8a)

Sure thing! Good luck.

Sharing things like cherry tomatoes and seedlings with neighbors could get them to owing you favors. Grass clippings, coffee grounds, watering plants when you're out of town helping with shoveling, not complaining about compost heaps ...

Liberty Hill, TX(Zone 8a)

I usually direct sow cucumbers rather then starting them inside, because they are fast growers. So you may want to supplement your number of plants by direct sowing some, when the weather is right. By doing this you eliminate having to have harden the plants off and there isn't any transplant shock.

Ramona, CA(Zone 9b)

I have 2 of the 48" T8 (cool shoplights) on pullies so I can get them close to the seedlings and I've been very happy with them.

This year, I need to grow about 300 plants for a charity sale so I need more lights. DH insists I need to buy T5's instead of T8's because they are more efficient. He bought 1 set so far and they appear to be much hotter than my T8's. I'm afraid that even if I keep them 18" from the plants (distance between rack rows), they may still get burned.

Has anyone noticed a huge difference in the heat output of T5 vs T8? Are there different types of T5 lights that may be cooler?

SE Houston (Hobby), TX(Zone 9a)

Check with drthor. She uses T5s on her beautiful tomato seedlings with great success.

Lewisville, MN(Zone 4a)

We have been growing seedlings for 25 years. All we use are cheap shop light fixtures. Run of the mill bulbs. They used to be about a $1 apiece. Probably higher now. The big thing is keep them close to the plants, like no more than 2". We space the shop light fixtures 16" apart.

SE Houston (Hobby), TX(Zone 9a)

Hey, Countrygardens!
I just ordered my T-Tape raised bed kit from DripWorks! Thanks for the tip! I think I'm gonna be happy with the system.

At least I'll be able to compare it to the AWS kit that BocaBob recommended. I bought it two years ago, and have never installed it. I'll use it on another bed, and compare the two systems.




Litchfield Park, AZ

I transplanted some cucumber and gray squash today, i just dont have the room inside for the big "pots" (milk jugs and two litter pop cut outs) they were dying on me so I thought I'd give them a chance outside.. i did harden them for a few days before.. its gettin warm during the day 70s ill cover them at night and hope for the best :), my peas are sprouting :)

Everett, WA(Zone 8a)

Wow, that 8 mil T-Tape can take up to 15 PSI!

I thought they usually ran around 4 PSI (and flow rates must have been pretty sensitive to even 1-2 feet of rise.

Good luck with it.

Ramona, CA(Zone 9b)

Country Gardens. I have to agree that the shoplights seem to work well. I bought the 2 I have about 5 years ago. I'm not sure how much they were but I remember they were very reasonable. They hold 2 T8 bulbs each and are reflective inside near the bulbs. I'd love to find more just like that but after hours of searching, it doesn't seem like they make those any more.

Thanks for the tip GymGirl. Drthor does have beautiful plants.

Liberty Hill, TX(Zone 8a)

The heat could keep the temps too high and give you leggy seedlings. That would be my concern, along with wasting money. Seedlings, once they germinate, are usually grown between 60-70 degrees. Too hot equals leggy seedlings.

SE Houston (Hobby), TX(Zone 9a)


What 1lisac said...

I just wanted you to see drthor's plants. Notice how high she keeps those lights away from the plants. I wondered why, until I realize how much heat the lights were generating. And, like 1lisac said, drthor moves her seedlings into a much cooler room to grow on under regular shop lights, after they germinate. She doesn't keep them under those lights for the duration. She only uses the T5s to coax them outta the soil...

With that said, I had considered converting to the T5s, before I know what I know now. I'm sticking with my plain old T12 shop lights for $10/kit from HD/Lowes. I can get replacement bulbs for $1/per at my local Habitat Restore. I use two kits side x side per shelf..To date, I'm up to 8 kits (16 lights). I utilize two shelves in each room.

Since my T12s don't generate that type of heat, I simply move them from my "warm" room to my "cool" room, and grow them on till time to harden off. They love the cool room, where they get to fatten up.


Irving, TX(Zone 8a)

I have just realized that you are talking about me here and ... thanks.

Let me correct this:
"drthor moves her seedlings into a much cooler room to grow on under regular shop lights, after they germinate. She doesn't keep them under those lights for the duration. She only uses the T5s to coax them outta the soil..."

I don't have a cooler room. I have only ONE room.
I start all my seedlings under T5 lights on my upper shelf until they are too tall. At this point I have no choice but to move them down one shelf where I have T8 lights. They grow ok here ... but not as well as under T5.

But no anymore ... I have just updated my second shelf to T5 lights.

3rd shelf maybe soon ...

SE Houston (Hobby), TX(Zone 9a)

Oh, ok. I thought you moved them into a cooler room.

Liberty Hill, TX(Zone 8a)

Where did I say that drthor moves her plants to a cooler room? Lol Thats what I do. I've learned that from reading seed starting catalogs and from commercial growers like Bernie and Shoe. When people due this for profit there has to be room to make a profit. Lol. I've always been told that I grow beautiful seedlings so I must be doing something right. What's the difference between T 8 and T 12 lights?

Charlotte, NC(Zone 7b)

Lisa - this will explain the difference better than I can:

My seedlings do grow much better under the T8's - shorter, stockier, greener.

SE Houston (Hobby), TX(Zone 9a)


I am SOOOOOOOOOOOOOOOO sorry. I mis-spoke. It wasn't you who said that. I said that! LOL!

Liberty Hill, TX(Zone 8a)

Thanks Bee, I guess I'm wondering what regular shop lights are T8 or T12? Thanks for the link. My regular old shop lights have always given me short stock seedlings I guess I never paid that much attention to the bulbs. Lol

Everett, WA(Zone 8a)

Old shop light are T12, that is, 1.5 inches in diameter or "12/8" inch). I thin k they go bacxk to the 1930s and are very inefficient compared to modern CFLs.

T8s are one inch in diameter: eight 1/8ths. They are more modern technology (CFL) and MUCH more efficient. They recently started coming down in price to cost little more thyan T12s.

T5 tubes are 5/8" in diameter. They are the newest technology, and arou8nd as efficient as T8s, on average. Some T5s are much brighter than T8s or T12s. Some are designed to have longer efficient lifetimes, or be extra-efficient over a standard lifetime.

T5s are still so new that they are still evolving (and more expensive.) However, don't be put off by seeing one T5 bulb cost twice as much as a T12 or T8! It is probably twice as bright and/or twice as efficient as a T12.

Lewisville, MN(Zone 4a)

Do they fit the older units ?

Durhamville, NY(Zone 5b)

T5's no. They need to be in lights made for T5s.

Everett, WA(Zone 8a)

Both T8s and T5s are supposed to need "electronic" ballasts like other CFLs.
Old T12 fixtures have "magnetic" ballasts.

However, the T8 pis "fit" he old fixtures, and I've read mixed things about whether that's just inefficient, or unsafe, or won't work with some kinds of T8s. One source claimed that the original T8s from Europe would "go either way", but that was just one source.

So I don't truly know about T8s, but I believe it's a bad idea (or very bad idea) to plug them into the wrong kind of fixture.

To get better efficiency than T12s, you have to use modern tubes AND modern fixtures. If you want something a lot brighter than T12s, you need to get T5s.

If you have T12 fixtures, and want something a little brighter, there are SOME modern T12 bulbs that are as bright as T8s - but the bulbs are more expensive e and they are not as efficient as T8s.

T-12 usually emit 2,100 to 2,800 lumens and consume 409 watts. Some pricy ones may put out high as 3200 lumens, or consume as few as 32 watts, but you can pay extra for EITHER brighter OR more efficient, but can't get both in the same T-12 bulb.

T-8 usually put out 2,725 to 3,000 lumens and consume 28-32 watts. And their price is coming down.

New kinds of T-5s keep coming out, many of them more expensive per tube. but they not be much more expensive per lumen.

T5s are about as efficient as T-8s, and you can get 5,000 lumens for 54 watts! Or more efficiency and less brightness. Or longer bulb life.

Liberty Hill, TX(Zone 8a)

Bernie, there is a new thread in the Veggie forum that talks about that.

Rick the T5s may be more efficient but I would have to replace so many lights and fixtures that are only used seasonally that there is no way I would ever break even.

Besides the ones I have work fine. I have great seedlings every year. If it's not broke I'm not going to fix it. I have also heard the T5s throw off a lot of heat. After my seeds germinate I try to reduce the temps for shorter, stocker plants. If I have to keep the T5s 18" from the plants it seems to me the extra heat and lite is going elsewhere and that seems wasteful. When the cheap shoplights no longer work I will look for a replacement. But after starting at least 10,000 seeds they seem to be doing their job.

Everett, WA(Zone 8a)

>> Rick the T5s may be more efficient but I would have to replace so many lights and fixtures that are only used seasonally that there is no way I would ever break even.

Yup! One of these decades they will start showing up in Habitat for Humanity stores, and then I'll swoop in!

>> Besides the ones I have work fine.

I suspect that the main benefit of increased brightness would be not needing to adjust lights as often, or keeping some vegetable types indoors longer. Or new fixtures might have only one tube instead of two per shelf, or support a shelf 22" wide instead of 11". Which way do you run your trays?

>> heard the T5s throw off a lot of heat.

I've also heard t6hat from just one person, but if they are more efficient than T-12s, how can they emit more heat? Maybe it is more heat per tube, but meanwhile the tube is putting out twice as much light.

Everett, WA(Zone 8a)

I forget if I siad this 10 posts ago or not, but it bears repeating:

The least expensive way to get more brightness AND more efficiency is to clean your bulbs and reflectors!
Next most expensive is hanging side reflectors so fewer photons escape.

Next most expensive is replacing your bulbs every 2-3 years if you're using it more than 6 months per year.
After around 15,000 hours turned on, a T-12 bulb is so much less bright and less efficient that you'll almost recover the cost of the new bulb in saved electricity costs. Waiting until black spots appear and the bulb actually burns out (20,000 hours) is wasting a lot of electricity and giving your seedlings less brightness than they could have. .

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