sunburn from led lights?

[incubator01]

I am trying to identify weather my 3 nagami kumquat seedlings are having sunburn from being 10 - 12h / day under a small LED growlight or if this is from something else.
They are not getting direct sunlight, however they are located near a window made of milk glass, so its completely blurred and milky white, the sunlight is heavily filtered.
The LED light I use is PARUS LED grow light SOL Series (PGL-E18) specs found in english here: http://parusplantlight.com/download/e18-specifications

I keep the plants definitely more than 20cm away from the light, when turning the light off at night I spray the plants with a foliar spray sometimes, rainwater other times to maintain moisture levels.
I water with rain water every 2 - 3 days a little bit because these things have tiny roots , the rain water is mixed with an auxine based root booster and once a week I add liquid fertilizer for citrus (planfor citrus , qualifies in most areas)
They're planted in seeding soil that drains very well and also dries out nicely inside.
However the first 3 weeks I had no sign of these burn marks, only since today did I notice it.
Thing is that this happens to every citrus seedling I tried so far, tomato or chili pepper seedlings do not have this problem.
Does anyone have a clue as to what is going on?
Attached are images of each plant.

[CanadianCitrus]

It’s only pumping 25 watts which is not very much right now. I’m using a 300 watt LED and I haven’t had any problems yet. Could it be damage from soluble salts?

[incubator01]

It’s only pumping 25 watts which is not very much right now. I’m using a 300 watt LED and I haven’t had any problems yet. Could it be damage from soluble salts?

Perhaps, I have no idea, that's why I put it up here, but maybe the nutrition I added has those.
Guess they're too young for that and I'll have to stick with root booster only then for now.

[poncirsguy]

Nagami and Meiwa kumquat seedlings are very difficult for the first 30cm of growth.  I gave mine 16 hours from a 23 watt daylight CFL set 4 inches from the top leaves inside a bright white chamber.  I lifted the plant so that a half inch of root was showing to protect it from damp-off disease.  I use Miracle Gro 24-8-16. with 6 plants in a 1/3 liter pot till they were 15cm-20cm tall.

[incubator01]

Nagami and Meiwa kumquat seedlings are very difficult for the first 30cm of growth.  I gave mine 16 hours from a 23 watt daylight CFL set 4 inches from the top leaves inside a bright white chamber.  I lifted the plant so that a half inch of root was showing to protect it from damp-off disease.  I use Miracle Gro 24-8-16. with 6 plants in a 1/3 liter pot till they were 15cm-20cm tall.

Wow, that's pretty strong nutrition, the liquid fertiliser (sunplant citrus) I use has an NPK 11-3-6 , the slow release I use has an NPK of 16-7-15,
My seedlings right now are about 3 weeks old, I read I should repot them once they have about 4 leaves but at what age did you lift this root?

[poncirsguy]

As soon as I had 3 inches of root.  Kumquats grow so slowly that it takes too long to get through the damp-off susceptible stages and are killed

[incubator01]

As soon as I had 3 inches of root.  Kumquats grow so slowly that it takes too long to get through the damp-off susceptible stages and are killed

ok, thanks, mine aren't that far yet, I'd say the roots are maybe almost 1 inch atm.

[Ilya11]

For me this is a damage due to  fertilizer excess.

[Millet]

I totally agree with  Ilya11, it certainly looks like fertilizer soluble salt damage.

[incubator01]

Ok, thanks.
I'll stop giving it for a while then until they're showing signs of deficiency.

[Millet]

I seriously doubt the slight damage to incubator's tree leaves was caused by LED lighting.  I agree the leaves show soluble salts damage from the fertilizer over supply.

[incubator01]

I seriously doubt the slight damage to incubator's tree leaves was caused by LED lighting.  I agree the leaves show soluble salts damage from the fertilizer over supply.

And I too agree with your conclusion.
To try out I planted some kaffir lime seeds in the end of august, atm 2 seedlings are growing slowly but healthy and 2 are about to stick their heads out.
I did not feed them with anything at all yet, (so for one month now I watered with rain water without any kind of nutrients) and I used a soil of seeding soil mixed with some coco fiber.
They're doing very nice, good green leaves, tiny but healthy. and I put them under 14h of LED light, even placed a second one next to it to cover larger area, no problems at all.
With the kumquat seedlings and even with some adult citrus I admit I probably gave too much food and that caused this issue.

So I will wait with giving nutrients until they grow 3 pairs of true leaves and then I start with liquid fertilizer, but one that is on the weak side, because if I give a strong one right away I might kill them again.

[catheshellman]

I suppose that sunburn can occur due to two reasons. The first is the one you mentioned, using incorrect light to grow sol plants. I have grown several different plants of this type using explosion proof LED flood lights and they took up the light quite well as the light is big and wide but not too strong and it spread evenly over each plant. And secondly, what the guys above have already said, it may be a trite excess of fertilizers, but I still lean more towards the first reason.

[incubator01]

I suppose that sunburn can occur due to two reasons.

I still think they died from too much nutrition like Millet said, the kaffir lime seedlings i planted in august (that I mentioned 1 posts ago) still live, though they haven't grown much yet, they are now starting, but a month ago I thought it'd be a good idea and give them a thinned out version of nutrition and root booster, I saw the same leaf damage appear not long after and some leaves were lost. But new strong vibrant green ones are growing back. These kaffir seedlings have been under a LED all winter btw.

Ever since I'm very careful with feeding seedlings, and nutrition in general.

But you did forget to add your "two reasons" so your post was incomplete

[pagnr]

What is the pot media they are planted in. Looks like 100% fine sawdust, peat or coir ??
You say Citrus has problems in it, but Tomatoes and Capsicum do not.
A small Citrus seedling will have a tap root well down into the pot thru various moisture zones, while a Capsicum seedling will have a more fibrous root system staying in the upper levels with better air and drainage. If you use the same media in taller narrow pots, the Citrus roots will be in a higher air zone for longer.
If possible check the pH of the mix with a test kit.

[incubator01]

What is the pot media they are planted in. Looks like 100% fine sawdust, peat or coir ??
You say Citrus has problems in it, but Tomatoes and Capsicum do not.
A small Citrus seedling will have a tap root well down into the pot thru various moisture zones, while a Capsicum seedling will have a more fibrous root system staying in the upper levels with better air and drainage. If you use the same media in taller narrow pots, the Citrus roots will be in a higher air zone for longer.
If possible check the pH of the mix with a test kit.

Those seedlings from the kumquat in the first post were still in seedling soil, so general seedling soil without adding coco coir or anything else.
My kaffir lime seedlings have grown beyond that stage and are already transplanted in soil with 50/50 peat/turface.

Regardless of the plant i always start out seeds in general seedling soil.

[pagnr]

Is general seedling soil a commercial product. If so any more details. Is it something normally used for flats and punnets ??

[incubator01]

Is general seedling soil a commercial product. If so any more details. Is it something normally used for flats and punnets ??

https://www.gamma.be/nl/assortiment/agrofino-zaai-en-stekgrond-40-l/p/B240061

there.
It's just standard well draining seeding soil mixed with some perlite.
Almost every commercial brand has some sort of seeding soil blend, not all recipes are the same but that doesn't matter.
The seeds germinated well in that soil; it's my fault the seedlings died.

Also the adult kumquats died too, they just couldn't handle our diverse climate, temp change and humidity and both a big 5 y/o tree and a 2y/o tree died, all leaves dropped and branches turned brown.

No kumquats for belgium that's for sure. I stick to Yuzu and shikuwasa, they work really well here

[poncirsguy]

Meiwa  and nagami are very hard to grow.  Fukushu kumquats grow much better.

[incubator01]

Meiwa  and nagami are very hard to grow.  Fukushu kumquats grow much better.

According to oscar tintori the Fukushu is unsuited to humid areas because susceptible to phytophera.
So also not good for my region.

[poncirsguy]

Meiwa  and nagami are very hard to grow.  Fukushu kumquats grow much better.

According to oscar tintori the Fukushu is unsuited to humid areas because susceptible to phytophera.
So also not good for my region.

I certainly hope not..  My healthiest trees are all Fukushu kumquats

[incubator01]

Meiwa  and nagami are very hard to grow.  Fukushu kumquats grow much better.

According to oscar tintori the Fukushu is unsuited to humid areas because susceptible to phytophera.
So also not good for my region.

I certainly hope not..  My healthiest trees are all Fukushu kumquats

Well I got it from here: https://www.oscartintori.it/en/prodotto/changshou-kumquat/
I know it sais Changshou but according to other sites this is another name for the Fukushu kumquat.
So if their info is inaccurate, shame on them

[poncirsguy]

Fukushu = Changshou  is correct.  My area is so humid I get  mold on my car body by early spring.  If your tree is grafted to phytophera resistant rootstock it will be no problem.

[incubator01]

Fukushu = Changshou  is correct.  My area is so humid I get  mold on my car body by early spring.  If your tree is grafted to phytophera resistant rootstock it will be no problem.

Well, like I said all the volkamerian or macrphylla rootstocks failed on me, my last kumquat died real fast in a few days, due to humidity. Same with many kaffir limes i had. Citrus on PT or citrumelo swingle perform much better here. They can take a serious beating before they die from moisture. And so far they're my favorite rootstocks
Granted I'm not as experienced as many of you, though I am learning and improving, but I quickly found out volkamerian and macrophylla were very sensitive compared to PT and citrumello swingle. Carrizo is also very sensitive, at least here, it also couldn't handle air humidity of 80% during early spring.

[Millet]

Thousands of citrus trees in Florida are grafted upon Carrizo. The humidity in Florida reaches up to 100%.

[incubator01]

Thousands of citrus trees in Florida are grafted upon Carrizo. The humidity in Florida reaches up to 100%.

but florida doesn't have cold temperatures in the winter / spring like Belgium. ther's the difference
Florida is citrus heaven, Belgium is not. As much as I wanted to grow other kinds here,  I just can't. Unless I invest in a complete isolated controlled environment.
So I have to stick with certain rootstocks and certain scions that are more resistant to our climate.
So far Yuzu & Shikuwasa are proving to be very successful here.
Poncirus by itself too, but mine doesn't seem to grow new leaves yet, probably because oscar tintori sawed off a lot of the thicker branches for grafting purposes.

[poncirsguy]

rootstock
https://crec.ifas.ufl.edu/extension/citrus_rootstock/tables.html

[vesteronys]

Spammer

[mollyparsum]

Spammer

[1rainman]

Yep 100% humidity and sun so powerful it will burn your skin in 15 minutes if you are pale and citrus like it. But citrus don't like sitting in wet soil. It's good to add some sand to the potting soil. They can dry out quite a bit between watering with no problem but damp wet swamp soil they don't like. Don't like mulch. Here in Florida yes high humidity and rains a lot but the dirt is sand so roots dry out between watering and also hot so it dries quickly. A seedling needs zero fertilizer. They will sprout in pure sand. You can fertilize heavy once the plant is big.

[1rainman]

There is a lot of variation in what citrus can handle the cold. Dwarf Meyer lemon is perfect for the north. Bring inside when temps go below freezing otherwise it does great. I had lemons in Ohio. It's small enough to grow in a large container and move inside in the winter. I used grow lights in winter.

Some citrus need hot temperature though. Lemons do not like cold but Meyer lemon is only 3/4 lemon. Nobody knows exactly but thought to be 1/8 grapefruit which is very cold hearty 1/8 tangerine and 3/4 lemon. I can eat these lemons they are only slightly sour due to being part orange or whatever. By far the best citrus for the north. I had a tangerine that did well but got too big. Grapefruit is probably the easiest citrus to grow that is good to eat in my opinion or a tangelo half grapefruit half tangerine. Or the Meyer lemon.

[incubator01]

There is a lot of variation in what citrus can handle the cold. Dwarf Meyer lemon is perfect for the north. Bring inside when temps go below freezing otherwise it does great. I had lemons in Ohio. It's small enough to grow in a large container and move inside in the winter. I used grow lights in winter.

Some citrus need hot temperature though. Lemons do not like cold but Meyer lemon is only 3/4 lemon. Nobody knows exactly but thought to be 1/8 grapefruit which is very cold hearty 1/8 tangerine and 3/4 lemon. I can eat these lemons they are only slightly sour due to being part orange or whatever. By far the best citrus for the north. I had a tangerine that did well but got too big. Grapefruit is probably the easiest citrus to grow that is good to eat in my opinion or a tangelo half grapefruit half tangerine. Or the Meyer lemon.

All of this depends on the rootstock.
Anything grafted on macrophylla or volkarmerian will die here, my pursha lemon on macrophylla recovered transplant shock but is now struggling to grow, despite well draining soil and dry conditions, it's pretty clear it wont survive another winter here.

I will no longer buy anything on those rootstocks.
Same with carrizo, too sensitive

Seedlings can get a very diluted version of food once they're a year old, been doing this now with great success in combination with a grow light.
They grow like mad.

[1rainman]

My Meyer lemon wasn't on any root stock. Generally root stock would get too big for a container and be root bound. Dwarf Meyer lemon only grew as big as the container and was healthy. Though it got fruit when in a big pot. It's the only one small enough for me to grow in a container and bring indoors.