LED Grow lights

[CrazyAboutOrchids]

WAY early to post thoughts, but I started my seed on 03/17 and currently have 38 little tomato, eggplant and a variety of peppers growing under one of the SF600. Wasn't quite sure where to place the lights so they are low to the plants and I check daily.

My growing shelves are in my basements where temps are probably what many would consider sub-optimal, but I like growing my plants in cool temps. Been doing it for years, I get real thick, solid stems; although growth is a bit slower, they always grow healthy so why fix what isn't broke?

My first germinated tomatoes are starting true leaves.

[svalli]

Few weeks ago I ordered two Cosmorrow® Led 40w UV LED-strips to add with my 14000K led tubes. These have 1/3 365nm UV-A LEDs and 2/3 6500K white LEDs. I was hoping that the UV-A could help with the intumescence, but it looks like it is not the solution to replace fluorescent tubes.

I looked from my old photos that Momotaro has suffered a lot, when grown under LEDs. I started two Momotaro seeds in RootIt cubes and transplanted those to 2" pots. I kept them on a shelf, which had two 13W 14000K tubes and one of these strips with UV-A. For couple of weeks things looked OK, until last Sunday both plants started to show edema kind symptoms on lowest true leaves. I started to then wonder, if the RootIt cubes stay too moist and if that could be causing the problem. This is the first year I had started seeds in them, so I have no previous experience. I then moved one of the plants on same shelf with rest of the tomatoes, where I have two 14000K led tubes and one 30W Reptistar fluorescent tube, which has 5% UV-B and 30% UV-A.

Just in four days there is definitely difference between these plants.

Momotaro 16th and 20th of April.jpg

The one which gets also UV-B has recovered and the one on the original shelf starts to look worse, with wilted leaves and the edema symptoms moving up. I feel so bad for that suffering plant, that I would like to move it too, before it is too late.

Sari

[bower]

Really helpful experiment @svalli .
I'm still using my old fluorescent tubes until I can figure out the LED solution for tomatoes.
I had some weird results with cabbages and other brassicas under LED this winter, that they grew downward instead of reaching for the light. That's the old single color LED shoplight though, which really isn't meant for plants. I didn't dare put it over my tomatoes, even in the window.

[pepperhead212]

I got some replacement T8 bulbs at Home Depot just before putting my peppers under them a couple weeks ago. All they have now is LED replacements - I think it's some law thing - and I was skeptical. They are only available in pairs, and the lumens they said they had is 3600 - I thought that might be for both! lol The output of the simple "60 w replacement" bulbs were never what 60 w incandescent bulbs were! But this surprised me - it was about like the good, newer T8 (that were in the lower 3,000s, in lumens) bulbs were like, when placed next to the old ones, when I took a photo. They also have a much longer expected life span. Another good thing - they sell large boxes of them, which are cheaper than the pairs, and much cheaper than the old ones. So eventually, I'll be replacing a lot of them.
Photo shows how much brighter the LED replacement bulbs are than old T8 bulbs. by pepperhead212, on Flickr

The ones I got are 5,000k, and the plants are definitely doing well under them.

[CrazyAboutOrchids]

My plants seem to be doing well under the Spider Farmer SF600's. March 30th I posted they were just starting true leaves. These are some of them today.... all about the same height at 5" from soil level. I'm not seeing odd growth or spindly growth, no reach, no twisting, they just seem normal to me.

[Yak54]

My plants seem to be doing well under the Spider Farmer SF600's. March 30th I posted they were just starting true leaves. These are some of them today.... all about the same height at 5" from soil level. I'm not seeing odd growth or spindly growth, no reach, no twisting, they just seem normal to me.

Looks to me like your SF600's are doing a fine job ! How far do you keep them from the seedling plants ?

Dan

[svalli]

I checked specification of the SF600 and it has 730-740nm IR LEDs. Some studies have found that the so called FAR-red wave lengths do inhibit the intumescence, when tomatoes are grown in UV-deficient environment.

There is a strip with IR LEDs in the Cosmorrow series, but I have already spent too much money on new grow lights this year, so I may invest in those nex year.

Sari

[Yak54]

I checked specification of the SF600 and it has 730-740nm IR LEDs. Some studies have found that the so called FAR-red wave lengths do inhibit the intumescence, when tomatoes are grown in UV-deficient environment.

There is a strip with IR LEDs in the Cosmorrow series, but I have already spent too much money on new grow lights this year, so I may invest in those nex year.

Sari

Heaven forbid the intumescence should be inhibited !

Dan

[CrazyAboutOrchids]

[/quote]

Looks to me like your SF600's are doing a fine job ! How far do you keep them from the seedling plants ?

Dan
[/quote]

I'm not really sure how far they should be away. The literature shows them like 12 inches up, but doesn't seem right to me. Mine are pretty close, like probably far too close, but today I gave them a few inches of space on my bigger plants. There is no heat so it's not like they are burning the leaves or anything. Everything seems to be doing well so, I guess why fix what isn't broke...

How close do you think they should be?

[svalli]

Heaven forbid the intumescence should be inhibited !

I'm sorry, but now I do not quite understand. Did I type something funny or use wrong words? English is not my native language, so my choice of words may not always be correct. It also causes that I may misunderstand jokes, if there is such here.

[Yak54]

svalli------No worries ....you are good, in fact very good ! My sense of humor can be odd at times and this was one of those times. I was poking fun at the usage of your word "intumescence". In 40 years of growing tomatoes I have never heard this word used. Probably my ignorance is showing. Please forgive me if I offended. Was not my intention. I have great respect for you and your country and welcome to NATO !

[Tormato]

Well, my shelving finally arrived. And, I have the grow lights, the seed starting medium, the small containers for initial starts, and the seeds.

It's just that it's April 20th, and I'll probably be starting seeds outdoors in about 10 days, like I usually do.

Since the shelves are adjustable in 1 1/2" increments, and the lights are adjustable too, I think that I'll read up on what to grow, how tall things will grow, what size permanent containers are best, what long term growing medium is best, what fert to use, etc...and set it aside until the fall or winter.

[Yak54]

If you start tomato seeds now, in 10 days the little seedlings will have their true tomato leaves. Wishing you a FANTASTIC 2023 growing season !!!


Dan

[svalli]

svalli------No worries ....you are good, in fact very good ! My sense of humor can be odd at times and this was one of those times. I was poking fun at the usage of your word "intumescence". In 40 years of growing tomatoes I have never heard this word used. Probably my ignorance is showing. Please forgive me if I offended. Was not my intention. I have great respect for you and your country and welcome to NATO !

All right, it was my misunderstanding

I have already become almost fond of that word, because I was battling the problem quite many years, before finding the name for it and what caused it.
https://www.merriam-webster.com/dictionary/intumescence

Earlier it was identified as edema, but it is actually different.
https://hnr.k-state.edu/horticulture-st ... demata.pdf

There has been recently many cases of such problems been reported in Finnish gardening forums. With high electricity prices and EU ban of fluorescent tubes becoming later this year many people have switched to LED-lights and commonly some cheap flood light type fixtures, which are not intended as grow lights. There has been problems growing tomato seedling also with 6400K lights sold as grow lights and some tomato varieties get intumescence. There is a lot of debate on those forums going on now, because some people have been able to grow successfully with same lights while others have problems. Difference usually is that the problem does not occur, if the LED-light is used just as supplemental light by a sunny window.

I noticed that those FREELICHT lights have also some FAR-red LEDs. If tomatoes grow well with those lights as only source of light, that 730-750nm may indeed be the needed wave length missing from my LED lights.

Sari

[bower]

I also had this problem before I had a name for it or any clue about the cause.
It is really getting urgent though for the LED makers to get some products out that are really suitable for tomatoes!
Some of the variation in intumescence problems will be due to genetic sensitivity among tomatoes.
Some of the variation may also be due to different growing media, watering regimes, and temperature. It's a challenge to keep small seedlings moist without overwatering, and if you let them get dry then there is a risk of intumescence upon watering.

[Yak54]

Sari-----Ok thanks for the education. I feel smarter now lol. Now if I only had an electron microscope I'd be all set.

Dan

[Yak54]

Sari---- In regard to your comment on the Freelicht lights. I bought one last year and used it for about 3 weeks to grow my tomato and pepper plants. It did a good job so I bought another one 2 weeks ago and I'm using it also this season for lettuce, tomato, and pepper plants. The one I got recently is brighter and better quality than the one I got last season. And yes their specs show the 420-470nm blue spectrum. I like the new version better than last years model but they both are working well for me so far. My biggest challenge has been learning how close or far the light needs to be from the plants. It's not the same as it was with T8 fluorescent where I kept them 1-2 inches from the plants.

Dan

[Yak54]

So far it looks like the sweet spot for my Freelicht LED Grow Light is about 8" from the tops of the small plants. I've had them closer and seemed to notice the color of the leaves tends to be a lighter green than when it stays at 8". Same deal for the pepper seedlings. It just means I have to learn the new technique with the LED's as opposed to the old fluorescent T8 tubes. No problem.

Dan

[TheMad_Poet]

Thanx to Sari for pointing me in this direction. Should have done the research on shop light LED's before I started. They worked fine on my onion starts, so I bought more for my toms, what a disaster. So what is the bottom line. Are the Freelichts the best out there for toms? Wondering if I should just go back to fluorescents? The ballasts on all mine were going bad, so decided to rewire for the LED's. I like to start my toms early and have large plants to put out. I find I get way better productivity (Brandywines especially, and long maturity types) with early starts. This year's cold snap kept me from using my greenhouse-not heated- as much as I usually do. I move them out every day, and back inside at nite. Another question, what is the coldest young tomato plants can survive? In the past it seems that I remember anything above 35 degrees F for a short time, was never a problem for toms, but my wife did some research and says 65 F? Any opinions on that? So much conflicting info out there. The greenhouse warms up nicely once the sun gets up. Lost half my 150 tomato plants to the LED's, the ones I saved are doing great now that I quit the LED's. ADD: My shelves are 4'x20", would one double Freelicht lite (dual bulb) cover this? or would I need 2 per shelf?

[CrazyAboutOrchids]

I'm using Spider Farmer SF600's. I have one on each of 2 shelves in my basement. They replaces 4 4' shop lights with T8's. First year with them and it's been a learning curve. I did start them all out real close, and they were still real close as of my post 6 days ago, but now the tomatoes are up high but the eggplant and peppers are still low.

I just checked and my basement temp is currently at 64 but was probably a degree or two colder a few weeks ago when my starts went down there. My plants don't grow tall and lanky, they grow short and stocky, I think because of cooler temps and good light. No real scientific proof of anything, but I've been starting my plants this way for double digits. I did my second potting up yesterday and noticed flower buds this morning on one of my Kosovo starts.

They will start spending days outside when the outdoor temps match the basement temps, but on a cloudy day for day#1 and build up. I am not sure of my plant out date yet, depends on overnight temps. I do have tunnels that I can easily pop on/off as needed.