May 7

Reflectors on T-5 High-Output Flourescent Lights (for Starting a Micro-Nursery!)


Edited: May 7

Are the reflectors worth it on these lights? I am looking for solid data. One company, recommended by someone in the microgreen business, "Sunblasters" work really well. I hear that standard nursery trays only need 2 of these bulbs. The Sunblaster that comes with a reflector claims a 300% lumen increase. I have a 300 watt LED, but want to use the Sunblasters for interlighting in my lower shelving. I am wondering if I should get 1 light per shelf with a reflector instead of 2 of the regular lights. Ideas welcome as well

May 8Edited: May 8

Season 2 Episode 18 at 16:36 gives a good view of Chef's T5 setup in his propagation room. It looks like that second shelf light has reflectors, and 2 4 footers. The dimensions of those shelves look like 4 side-by-side nursery tray equivalent. It looks like he has 2 56 watt bulbs over 4 trays, which would break down to about 28 watts of reflected light per tray (approx. one, 2 ft bulb (24 watts)). I think. 🤣🕊

Thank you. A very interesting example. His plants look great here. The two bulb standard for nursery trays seems like the right idea. I have heard a lot about the 8-bulb standard for plants in general (6 blue and 2 red bulbs) over a 4x4 area is a good model too. For nurseries that is. I would think 4 bulbs per nursery tray would be optimal if you can afford it. I found this website useful for understanding different light intensity measurements... I also found this hydroponics website useful for understanding how to apply light intensity measurements... It seems other than wattage, that spectrum is the main concern. Quality overall is too so you don't burn the house down I would add. Just saying because I almost got some 20$ 2 bulb T5s for the micro-nursery but a lot of people were saying they melted in the sockets, was sparking, etc. I just ordered the Sunblaster w/ reflector for way too much money simply because they don't have a track record of catching fire due to poor manufacturing quality. The overall idea seems to be that you want 25-30 watts per square foot for fast growth, or more if you are supplementing CO2 to a heavily photosynthesizing plant like cannabis, sunflowers, etc. Seedlings, when they need light to germinate, can use less. But I assume plants will simply need more light than 12 watts (as is in my case w/ the Sunblasters I just ordered, 24 watts over 2 sq ft) as they develop a few sets of true leaves. I have 2 emergency clip on lights. Maybe I will apply those Not getting paid to endorse anything, just organically testing the market here.

No sales pitch detected. Sunblaster has a solid reputation and seems to be in a lot of hydroponic stores. I don't recall any complaints about them. I have read the reviews about melting and smoking from some others. As I was looking at Chef's setup, the top shelf lights may not have had reflectors. I'm thinking the reflectors may not make much difference. 25-30 watts per square foot seems about right 1 foot of bulb over each half of a tray or a single bulb longways. Some of the lids even have grooves on top for the light to lay right on the lid. Thanks for the links.

Yeah a good rep. Yes the reflectors are not quite as great as I was thinking. I had just heard good things about them. Lumens apparently don't tell anything about light for plants however, so a 300% lumen increase doesn't really mean anything. I got the one with the reflector anyway, I really just wanted to see if I could make good seedlings with just one light, and figured I'd try to optimize it. We will see how it goes... Probably could have just taped some tinfoil to the walls and it'd be the same... But I don't want to and the white on the walls already does a decent job of reflecting light! No prob on the links!

May 21Edited: May 21

I realized that one T5 is not enough for my seedlings. I quickly ordered another. I also got diseased peas because I was not careful about making sure I had a fan on the greens for a few days. Whoops. I really hope the second light stops the stretching anyway. I think I can do two lights for two trays as I have seen other growers do that successfully, because if you set it up the right way, both trays get 2 lights. If I am not impressed, I will be switching to LED's permanently. I was not very impressed with the results of the single T5 w/ mirror reflector. I read on SF Gate's website that lights with small reflectors (such as Sunblaster's T5 has) should use white instead of mirror reflectors to increase the distance that the light reaches. Even though I have white walls in my grow room, it seems to me that the mirror reflector does narrow the light down to be effective (stops stretching) only within 2" of it, basically the width of the reflector. Anyway I saw other growers successfully using the reflector version of the Sunblaster T5 (2 bulbs per tray) so I'm hoping mimicking success leads to success here...

May 23Edited: May 25

Alright update... I uh am using two T5 sunblasters when I realized they weren't 2 feet, which I needed. Therefore, seedlings lean in from the sides of the tray a tiny bit. I think I'll keep these bulbs because the plants are doing okay overall as seedlings, but I am not impressed for $75 at all. I would HIGHLY recommend using LED's or at least a different brand instead. t's absolutely insane to have to spend $100+ on a light for a micro nursery with a tray or two. Like, absolutely fuck that and fuck Sunblasters for being a bunch of pawns and charging so much for weak ass lights. It should say "for microgreens only" on the packaging... Just wanted to add... These lights actually are perfect for microgreens, they encourage straight upwards growth and a beautiful light green color. Unfortunately, legginess is not what I want in my nursery, although that may be a good thing for microgreen growers.

Amazon is selling 1 four ft long Sunblaze for $38.35 shipped. That's 4 feet of 54 watts. Two trays (end-to end). Thanks for the helpful thoughts. I would love to see Mars Hydro come out with a longer light for seedlings. Something like half of SP-150 and longer spread.

Thanks for that @plant medicine heals. I was literally JUST thinking Mars Hydro. I was hoping Mars Hydro would have something because they're a pretty trustworthy brand. Unfortunately, I need no-heat lights essentially for my micro nursery, I simply cannot run the 300 watt LED without overheating the nursery, unless I cranked my A/C which I don't want to considering I have mushrooms that need slightly higher temperature. I got some LED lights to supplement my current sunblasters (adding about 10 watts, or one strip blue+red LED), and then 50 watts of LED on another 2 foot shelf. We will see which does better, supplemented T5s or just LEDs alone, they will have equal wattage approximately (give or take a few watts). Will update!

Jun 8Edited: Jun 8

aaaaaaaaalrighty then. Test results, bottom shelf of 2 ft width HDX shelving unit: 4 of the 6 LED's 6 inches above the growing tips of my plants caused some chlorosis/gnarly hyponasty in my tomato plant but the lettuce and squash seemed to enjoy basking in em a lot. It could have been that the tomatoes were simply a little taller. At 6 inches, the light strength is 4x what it would be at 1 foot, potentially too much. That'd make a 10 watt light act as a 40 watt light. My other shelf (middle shelf), w/ 2 sunblasters and 2 10-watt LED bars (@ approx 12 inches) still had an unsatisfactory response IMO. While not as leggy as before, my seedlings are still slightly leggy, which is really the #1 thing to avoid in veg. The good thing is, the lettuce seedlings developed much thicker stems in response to the lights, indicating satisfactory blue light levels. Solution: Combine all 8 lights (6 10-watt LEDs and 2 24-watt sunblasters) 1+1/2 feet above the growing tips of my plants. This will reduce heat significantly which was near impossible to keep below 78 F (maximum safe temperature) at less than 1 foot away. This will also provide enough light to my entire 2 10x20 trays because I will strap some lights to the outside edge which will hang over the edges of the trays, where the plant stretching is the worst. With this setup, I will be achieving 108 watts / 2.778 square feet of trays = ‭38.877 watts per square foot of tray. This is technically a little overkill wattage wise, but I am so tired of not having enough light I really just want the damn thing to work well so a little overkill, as long as it's not harmful, will help me achieve that. Plus, I can easily get over well over 150 plants started in that space, up to 400 would be the absolute max, 300 being within good reason though. PS, this is also my blow drying station for my salad greens pulled from the garden post washing and salad spinner... I have a 10x20 fan for drying greens on the top shelf if you were wondering. I protect the lights and plants below w/ tinfoil below a raised drying screen on the top shelf. Taking away the middle shelf of plants/lights will allow me to put the tinfoil a level down, so the air can penetrate much further through the top shelf's raised drying rack, hopefully speeding my drying process as it is the real bottleneck on my operation right now. Anyone ever think they can have a nursery and drying rack in the same rack!?!?! Only problem is the rH, it spikes about 10% by the end of the process. Could cause disease vectors if your plants are not already very healthy. Link to the lights I bought: If I still have stretching, I will be returning all of these lights and attempting to find something else, probably a 2 ft 8 bulb T5 fixture.

So I tried the lights, all 8, at 12 inches away and still got stretchy seedlings. I'm disappointed. They aren't bad, but definitely not short and squat like I want. Some are pretty bad even depending on the plant. Tat Soi for instance, seems very unhappy with it. I am now trying them about 8-10 inches from the lights. The temperature is now 78.2-80.2 F. Before it was consistently below 79F at 12 inches away. Just an update. I will see how this goes.

Jun 18Edited: Jun 18

Grow them little bushes, man. I'm not sure the T5s can grow bush. You think some of it might be genetics? Troy is growing a little bush on his IG channel.

Jun 22Edited: Jun 22

I'm not sure, it may be genetics. I realized my seedlings may have stretched because of not only the limited light, but because I planted many seeds per cell, which caused a lot of competition in each cell, particularly the Tat Soi. As soon as I thinned them, which I usually wait till the first true leaves to do (at least when I plant less seeds per cell), they stopped stretching. So it seems the lights may be adequate, but barely. That's 8 bulbs. I think I'll just do straight "300 watt" LEDs in the future, mine has never disappointed. I gotta wait till I have enough room to vent the room better though. Couldn't even fit my 3x3x6 tent in this space

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