Growing under LED light

I started few plants for early crop and noticed that my Tumbler tomato is curling a bit by the end of the day and straitening up by the morning. I did some research and decided it is too warm under fluorescent light, so I bought growing LED light like this:
Next evening my tomato was like one big knot, especially very top. It got better in the morning and back to the knot again at night. I started to think the problem is actually in the light itself. Anybody had similar experience? And what is a proper distance for LED light to the plant, same 2-3 inches as for fluorescent?
Now I set up different type of LED grow light - blue and red stick, will see how my Tumbler feels tonight. Now it is almost untied.

1 Like

Yeah you are way too close. Pull back to 10" and then adjust up or down from there based on how the plant looks. Keep in mind the spot growlight you purchased will only cover a bit more than a square foot area.


Yes, this is what I tried to cover - just one pretty young tomato. I read some review - looks like people don’t like this one on a long run, plants doing poor on it comparing to fluorescent lights. Will see how the sticks work…

I am using 300 watt LED’s for my seedlings with excellent results, better than any light I’ve used before. Mine are full spectrum from the brand roleadro, got them on amazon. They have to be like 30” or more away from the seedlings they’re very strong. 600 watt double that. Not sure about your light though.


Also see:

I’d hate to over-promote a product but if its in your price range I would strongly recommend the HLG 65 grow light. (Not going to post a link, but its easy to find) @scottfsmith is start seeds with one but you can easily grow a full-size tomato plant with them as shown in this comparison video:


@galinas, i am 99.9% sure that your floro light were not overheating your seedlings.
at one point in my seedling growing hayday i had 70 4’ 2 bulb fixtures with most if not all of them touching the plants. i had all fixtures 4 deep side by side and the heat was never an issue. with that being said if the temp of the room is say 100 without the lights then the heat from the light might be a problem. if all you are doing is growing a few seedlings to plant out in the garden when its time you cant beat a 4’ floro. now if you plan on fruiting them through the winter thats a whole diff story.

1 Like

Dimitri or scott: Not to hijack but I have that 65-watt light–any reason the plate has an outlet on 2 sides instead of a single plugin for the power cord?

My guess was you could chain power to units using a larger single power supply … no documentation on it was with the light though.

I still prefer my T5 HO Fluorescent.

By the time they ready to fruit I hope they will be on the deck, in the greenhouse. I am just experimenting with lights. But curling effect looked like it is correlating to light change.

I did a bit more research today and found this regarding tomatoes curling down:
From this thread:
I had a similar problem two years ago, and took some leaves up to Cornell Horticulture Department. This sounds very strange, but when the tomato plant top growth exceeds the root development, the plants react by reducing leaf surface area exposed to the sun until the roots catch up. It is usually brought on warm temperatures and too much moisture in the pot. They told me to ease back on watering, get my greenhouse temperature down a bit, and the leaf curl will just go away on it’s own. I planted-out the tomato plant, and sure enough the leaves straightened out and it was fine. This may not be what’s happening on your plant, but Cornell said that curled-down leaves are definitely not a result of disease. It is either a normal plant response or nutrition related.


This is the greenhouse complex at Chena Hot Springs, 60 miles east of Fairbanks AK. They supplement the little daylight they get with LED for baby greens and 6500K fluorescent tubes for cucurbits, modest size tomatoes, etc.


@scottfsmith is correct, the connections are parallel so you can daisy chain multiple boards together provided you have the correct power supply.

I feel like if you aren’t going with one of the recommended lights, it is definitely much more confusing to figure out what is going on. I’ve replaced all my T8 bulbs with LED replacement bulbs (22Watt at 6000K), on one shelf plus some self contained “T5” Led type fixtures (18Watt at 6000K) on the second shelf and I’m trying to figure out if it is too much light, not enough or just maybe not the right spectrum. To do it again I might bite the bullet and pay for the HLG fixtures, but that would have been about triple the cost.

My kales and chard look good, although maybe I should have waited to start them since it is staying pretty cold here and I can’t find a good time to harden them off. I had the flash on the camera so they are a bit washed out in this photo.

But my tomatoes are looking sort of twisty and the color doesn’t seem great. Too much light maybe? I just raised the lights a bit today and we’ll see how they do. I just dread getting leggy plants so I don’t want to have the lights too far away.

And here are some peppers that were getting quite purple until I moved them further from the lights. You can see the new growth is coming out green. They were previously under the other section that was definitely more lumens. These chinense types that are long season so they were started earlier.

Thoughts? How far should the lights be up from the top of the seedlings? Or might it be something else like too much water, they need ferts, or …? I just feel that with the old fluorescent T8s I knew what to expect. I’m sure by next year I’ll have a better handle on it, but want to make sure I’m not messing up the plants too much this year.

1 Like

I think you are worrying too much. Your tomato seedlings look almost exactly like mine, purple stems and crooked. Pretty sure that’s normal, and could be due to low air temperatures. Peppers look very healthy and dense - although farther along than mine so I’m a bit jealous.

6" from the plants is pretty safe. I’ve only had damage from LEDs when the plants grew so tall they got burned from actually touching the light.

Thanks for the reply. I probably had them only 2 inches or so above the plants so I decided to raise them up to about 7-8 inches for a few days and see how it goes. I’ve also been running the lights about 15-16 hours a day, so based on the purplish leaves on the peppers I’m hoping that helps. The tomatoes definitely looked more twisty by the end of the day, which also made me think too much light intensity.

Since nothing was looking too leggy, hopefully a few days with the lights further up won’t make them stretch out too much short term and I can see how they react. I actually haven’t fertlized the tomatoes at all and they’re in ProMix so no nutes to begin with, so I’ll give them a diluted nute snack next time I water as well.

@zendog, if you are using floros put them right on top of the plant. usable light emitted from floros diminishes rapidly every inch they are away from the plant.

I’ve got the YGROW from Amazon…i believe it is around 150 watts, but i haven’t checked it on the killawatt. Seems to be working ok. The first LED i’ve had for grow lights. I just let it run 24/7. My tomatoes don’t look super awesome, but they are still small and the room is quite chilly and they aren’t on a heat mat anymore.