Lights being 27-28" is too far for any benefit to plants, IMO. I did not hear about farina burning off yet. It is there to protect the leaves. I have burned plant or two from lights being too close, but they were really close (like 1-2") and under lights that emit heat too (in my case, it was CFL bulb; 150W equivalent, and I forgot about moving plant to it's spot as I was poking around...) Is it possible that farina was rubbed off?

I use lots of lights, and many are as close as 3-4" to the plants. No burning, decent growth and color on plants.

3-4" would be way too close for any decent powered LED. I can't comment on the weaker ones, such as shop light replacements. But I agree that 28" is way too far away for anything except high intensity discharge lighting!

If you have plants with different light requirements, you can raise up the ones that need stronger light by putting something under their pots. Light intensity drops off very quickly as distance increases with artificial light, so you would end up with stronger light reaching the raised ones, and weaker light reaching the ones below.

Having plants with very different light requirements in the same pot (if that is indeed your situation) just isn't going to work well.

Hi thank you both for your help! I'm attaching some pics for you to see what i'm talking about:

1. When i had the light about 16 inches away from echeveria imbricata the farina started burning away in larger splotches (tips of leaves). Then I moved it 18-20 inches away and it still happened, but smaller little circles, so less severe (towards center of leaves):

2. Here it is again on perle von nurnberg at 18-20 inch distance. (the center is starting to look better again after moving the light to the 27 inch distance.

didn't take a pic of the sedums (sorry), but needless to say they are losing their color at this distance. They are all in the same pot so can't be raised, but i guess i could move them, but then i wouldn't have a rainbow succulent bowl- lol. Sigh, i thought succulents were supposed to be easy;)

I keep plants under lights while indoors, and did not loose farina from lights yet. I do not know what happened to your plants - leaves look like they were sprayed with something. Obviously, I could be wrong...it just sounds unusual.

I just checked distance from lights: this one is 4.25", under 2 LED tubes (6500k, 1550 lumens each). Showing close-up of plant, and the distance - not best photo, light fixture is white but showing dark:

thanks for the info- what is the exact brand/type of your led tubes? Maybe i'll try that instead because yours look great! I'm thinking maybe the wattage (50Watts) is too strong and i should get a lower wattage? I am almost positive it is the lights (haven't ever sprayed anything) because changing the distance of the lights is improving the farina (for the new growth). BTW- what is the name of the top echeveria?- its really pretty!

one more question- sorry!! How many hours per day do you keep your lights running? Thanks so much again!

LEDs can vary a ton.. what exactly are you using, katie?

this is what i'm using now:

50W LED Grow Light Bulb for Indoor Plants, Led Plant Lights Full Spectrum for Vegetables and Seedlings, Plant Growing Light Bulbs for Hydroponics Gardening (Grow Lights 2019 Upgraded)

I am quite surprised that that light is causing damage at 18" above your plants. Are you absolutely sure that damage didn't come from something else??

katie

I do not think 50W is too much. I have few different types; another bulb is T5HO that is 54W. Plants are anywhere from 3.5" - 5" from it. I also use many CFL bulbs; they are min 23W (equivalent to 100W incandescent) and few are higher. There is more heat from these, and plants are 4-6.5" away. Tubes I mentioned are actually replacement for T8, they are GE. All my lights are on timer, 12hrs on/12hrs off. If you can, lower the lights but do it gradually - maybe about 12" for approx. a week, and than down to 8" or so, and maybe even lower. I hope someone will comment on farina - I really do not think it has anything to do with lights, but that is JMO :)

I am not absolutely sure, but 1st plant is probably Echeveria imbricata.

I'm certainly no scientist, but it seemed like the damage to the farina changed based on the light conditions (i.e. - smaller circles of farina removal at further distance and no removal on the backs of the leaves)- i didn't change any other variables. Also, I have moved a couple of especially damaged plants to a south facing window and the new growth has no farina damage whatsoever in the natural light. See perle v nurnberg below:

Anyway, I forgot to say thanks for letting me know what you’re using Rina. I may try that next time instead of what I have (maybe I’ll get one of those suspension bars to hang it from or something.) I’m thinking the tubes must distribute the light more evenly rather than a bulb like I’m using, which I guess must have a spotlike effect (although it shouldn’t because the light is stated to come out at an angle, but nonetheless. . .) anyway thanks again!!

Although I do not know what is causing those spots but I can say a few things about lights. A simple rule of thumb is to consider about 20-40 Watts of 'actual' light per square foot. The rest of the post is a simplified view on lights for plants.

First, the light you are using is not really 50W - from the questions/answers on Amazon I figured out that it is 15W actual power draw. That sounds about right. 50W is pure marketing gimmick like most led grow lights being sold. If it was a real 50W led then at 2-3 inches from plant it will fry the plants in a short time. You can keep a real 50W light higher up so that it covers about 2-3 square feet.

That light can be kept a few inches (eg 6inches) above most plants and it should be OK to light at most a square foot of canopy.

As you conjectured, spot lights throw a more intense light in a smaller area. The center of the spot will be more intense than away from it.

Linear tubes spread the light. So a 4 ft two tube T5HO will spread the light say over 4-6 square feet (with the light being about 4-6 inches above canopy). So it will be about 108W over 6 square feet and it will be 18W per square feet similar to the light you have.

The actual amount of light varies between types of light so comparing wattage is not very accurate but gives you a ball park estimate. That is because light producing efficiency of most cheap flourescents and leds in the market are quite close to each other about 70-90 lumens per watt. T5HOs and some of the better leds can do close to 100 lumens per watt.

Did not see Rina's post. She gives a good explanation of how light coverage varies with height and form factor of the light fixture.

Did you use any horticultural oil on the plants, or could they have been splashed by something such as a cleaning product or air freshener used within a few feet? Sprays can travel farther than we realize. As far as the light goes, correlation does not equal causation.

Hi igteacher- I promise you nothing was sprayed near them- i would know too because i'm the only one who does any cleaning in our house;)! Also, since it started happening, i would rotate the pots to avoid the more direct light on the succulents starting to show damage in the front of the pot. Then, it started happening to those succulents in the more direct line of light (previously facing sort of away from the light in a round pot). I hear you about the correlation/causation- I'm definitely not ruling out other ideas, especially since i seem to be the only one on the planet who this has happened to!!!- I've done countless other internet search's and have found no one else reporting this problem! I'm about ready to give up on these succulents! - might give it one more try with the led tubes. I would try other types besides led, but i'm afraid my husband might start noticing a higher energy bill. . .

thank you Rina and Tropicofcancer for the in depth explanations- very helpful!! So, it seems, based on your helpful research of the product, tropicofcancer, that it would be even less likely to be the lights if they are out-puting much less wattage than stated! Sigh, i just don't know what else it could be - i am sure of no sprays nearby, though. Also, If that were the case I would think it would have appeared more suddenly, not gradually appearing and worsening (circles enlarging) day by day. I am going to try the LED tubes as a last ditch effort and if i still have problems just make peace with my brown thumb:(

tropic

You explained wattage of lights better than I could :)

katie

I believe that LD are most economical to use, and supposed to last long time too. They are more expensive to buy. Bu your hydro bill will be les using LED than CFL. I m still using them, since I have quite a few left from initial gift...

thanks again rina for all your help- i inched mine back to 24 inches above and will keep going a bit more if i don't see the problem recurring (even though it might not be the lights- just in case!). and i still want to try the longer tubes at some point (when i feel like shelling out more money:) )

i actually found this statement from thesucculenteclectic.com: · "Grow lights should be
hung a short distance above your plants*. About 6 -12″ for fluorescent bulbs,
18 – 24″ for LEDs, depending upon the fixture." I still think it's possible that maybe the 16 inch distance did do some damage at least in the most direct area of the spotlight (even if the wattage isn't accurate). Still, no one else seems to be having problems at that distance but me- so again maybe it wasn't the lights. . . maybe this mystery will never be solved. . .

Height for LED lights can vary tremendously depending on the makeup of the light, which is what the "depending on the fixture" disclaimer refers to. There is probably more variability among "LED lights" than among any other type of light used for growing plants.

For instance, I have a 54 watt LED that actually uses 54 watts. I use it for my propagation, and it stays 24" above the cuttings (since they like slightly lower light levels than actively growing plants). It covers a 2 foot by 2 foot area at the light intensity I need.

You are using a significantly weaker light than I am (15 watt actual usage, as tropicofcancer found), hanging it as far or farther above your plants than I am (remember that when the light is farther away, the light reaching your plants is weaker), and your plants are mature, actively growing plants (not unrooted cuttings) - which need more light than mine do. That equation simply doesn't add up to "damagingly high light levels" on your end. Honestly, it doesn't even add up to "enough light" !

Hope you figure out the cause of the damage though!

you make very good points illsstep. I do wonder if there is a difference between power output and the amount of power drawn through the outlet, though. The seller themselves said it drew 15 watts, so they are purporting that it outputs an equivalent of 50 watts- not sure how that works. . . or if it is just a big gimmick or whatnot. Regardless, i will say that even though it has been at about 27 inches for about a week (i just moved it back to 24 inch distance today), nothing has etiolated, so the grow light is still doing some good at that height. Before i got the the grow lights to begin with i noticed etoiliation in the p.v.nurnberg in only a couple of days, so at least its preventing that from happening until i figure out what to do. . .

LED light fixtures are prone to mis-advertisement of wattages. The reason is that the LED diodes run most efficiently, and for the longest time, if they are not run at full power (wattage). But they do have a "full power" wattage, even if it isn't practical or energy efficient to use.

Lots of LED light fixtures advertise the maximum wattage of the LEDs, rather than the wattage they are actually run at to produce the most efficient light output. The wattage they are actually run at is determined by the parts inside the light fixture, and is usually not something you can change, so it's pretty misleading advertising.

Just remember that for artificial lights of all types, wattage and light output are two different things. Some types of lights are more efficient at turning power (wattage) into light than others - the others produce less light, and more heat, per watt used. This is why comparing lights by comparing the wattages isn't always a good idea, and why lights don't "output" watts. They output light and heat.

huh- how frustrating! thanks for the info!

If you have the yellow light version of the led (from the link you posted) then that could be the problem. You would need the white light or light with lot more blue in it. Yellow or warm white lights do not have sufficient blue light. If you have small area to cover you can use a clamp light fixture like this:

https://www.homedepot.com/p/HDX-150-Watt-Incandescent-Clamp-Light-HD-300PDQ/205031467?MERCH=REC--PIPHorizontal2_rr--202847393--205031467--N

You may find it cheaper elsewhere. And use 100W equivalent daylight CFL or LED. If you want tubes, Costco has 4ft two tube led light on sale for $20. I prefer the tubes when you have several small plants of similar height. You can have them a few inches off the top of the plant.

well shucks!- i was so happy i found the white/yellow light because i'm not a huge fan of that purple glow most have. It did say full spectrum, but obviously i didn't look closely at how much blue/red wavelengths were included. . .

I actally have the bulb in an adjustable arm desk lamp with clamp, so i'm good to go there, but not if i want to try the tubes. The frames are kinda expensive though. . . so i might try one more bulb. . .

i found this one on amazon and the very first review was pretty convincing:

https://www.amazon.com/dp/B0748D2SMB/?coliid=I200G2XD33HEFB&colid=3NHSF4Q4LQ3MX&psc=0&ref_=lv_ov_lig_dp_it

ever heard of it?

Thanks again for all your help!

I am not a fan of the purple glow (those lights are often referred to as blurple) either and that theory of blue/red being the only light that plant can use is considered questionable these days. I do have a couple of the blurple lights - different manufacturers. They are OK nothing spectacular.

Read the review of the Taotronics light and to me it sounds a bit hyperbolic. For two or three small plants it is probably OK. However, the point the person noted is something to consider: It is a spot light and the most intense light is in a small spot. The measurements noted there seems that it is quite intense in the center - close to sunlight at a foot distance !! That makes me question the results. I did like his detailed explanations and sounds like he knows what he is talking about.

How many succulents you have? What is the area that you need to cover?

I have 3 bowls and the area it covers is 18 inches long (front to back) by 12 inches across. I inched the light down some more based on everyone suggestions to 20-22 inches above the area this morning (still too afraid to go back to the 18 inch height!). I positioned the light centered crosswise, but closer to the front of the bowls at an angle so it is shining down across the 18 inch length from the middle. So, the ones in the front are closer, but getting less intense beams and the ones in the back are further away, but getting more of the intense "spot like" effect. I'm guessing you're going to say i need 2 lights. . .

If i do go with led tubes, would one 2 foot tube cover a 24 inch by 12 inch area? Or would i need 2? and what height?

Thank you thank you!!

You have far more experienced people helping you out, but if you just want to try another bulb I'll mention that I have this fixture:

https://www.amazon.com/Relassy-Spectrum-Gooseneck-Replaceable-Professional/dp/B07C68N7PC/ref=sr_1_4?s=lawn-garden&ie=UTF8&qid=1547675413&sr=1-4&keywords=relassy+led+grow+light

You can get just the bulbs or the whole fixture for a reasonable price. It produces white light, not purple, and I have a few succulents and other plants doing very well under them.

Thanks, Elena!- I welcome all advice! I actually almost bought that one, but for some reason i went with the other white-ish led light instead- guess i thought the extra 5 watts might make a difference. i probably should have picked this one instead now that i found out mine only outputs 15 watts because yours states that it outputs 20. How far above do you have it positioned?

Thanks so much again for your input!

I would say two spots or two tube 2ft lights. This will cover your plants properly. I am assuming all your plants are sort of similar heights. The two spot configuration allows you to adjust with heights a bit easier. What katie posted gives you that flexibility too.

But consider this also - you will soon want to expand your collection. I was thinking this light may be appropriate (it is T5 light not led): https://www.amazon.com/Light-4lamps-DL824-Fluorescent-Hydroponic/dp/B009GU4RMC/

It has 4 tubes and you can switch on/off two of them at a time. This will give you more flexibility if you feel like expanding a bit and some flexibility in deciding how much light you want.

I keep it about 8 - 12 inches away.

Thanks Elena- i must be doing something wrong with my lights to keep having this weird problem!

Thanks, too, tropicofcancer: the fluorescent lights are something i haven't tried. $54 for the whole system including 4 light tubes is not so bad- the only thing is i have nothing to hang it from so would also have to buy some sort of frame. At this point (this is my 4th light in a short span of time and i keep having the same problem with each, but less with the one i have now), i have spent much more on lights than succulents! Considering they will only be inside for one season (give or take a bit), I think my main goal has devolved to just not destroying them until they can get back outside. . . seems like a more realistic goal for me:) I'm even toying with the idea of breaking them up into small pots and squeezing all into my few south facing windowsills- at this point i'd rather them etioliate a little bit than lose the farina.

I do have a bit of an update on the farina which has me convinced that it is the lights. . .

so, last night, i added another light (from my collection:) ), because the stuff on the back sides was starting to etioliate (no surprise to you i'm sure!). but i accidentally had it angled slightly too directly towards a new echeveria (young leaf propagation) and the farina burned (IMO) away from the top leaves. It had already happened to the bottom leaves on previous attempt, but now the new growth has joined the fun! i should have rotated the pot away!- ugh!!

Anyway, the topsy turvy right next door seems fine though (its also a little further away from the light) so maybe the young ones are the most susceptible like someone said. Or it might be the particular light i used: https://www.amazon.com/gp/product/B07BVTJ6MK/ref=ppx_yo_dt_b_asin_title_o05__o00_s00?ie=UTF8&psc=1 Maybe too intense in a small area/beam of light?

Here's the pic: