50W LED grow light distance

[Whitefall]

Hi all,

I've bought two 50W LED grow lights to help my 2 bonsai trees growing indoors (Brush Cherry and Chinese Elm). These are the bulbs.

I live in an apartment with north facing windows and no garden, so grow lights are a bit of a requirement.

I've put them in the tallest desk lamps that I could find. The furthest I can get them away from the top of my trees is 10 inches. Do you think this is too close? I don't want to bleach/burn the leaves. It's not heat that I'm worried about - they run very cool, it's more the intensity of light.

If that's too close I'm not sure what I can do (short of hanging something from the ceiling - something I'd like to avoid in rented accommodation). I guess I could find a really tall floor lamp and re-arrange things.

I'd appreciate your insight.

Thanks,
Whitefall

 

[Paradox]

Nope 10 inches should be fine and preferable to hanging it from the ceiling. It will become a problem if the trees grow tall enough to burn their top leaves on the lights.

Here is my winter setup for my tropicals:

 

[Whitefall]

Thanks for the reassurement Paradox, that's a lovely set up that you've got there!

From a heat perspective, with these LEDs if they're more than 1 inch away, heat is a non issue.

Distance seems important to allow the colours of light to merge, and also so that the light isn't too intense so as to burn the leaves.

Hopefully this will be fine as you say

 

[Paradox]

Thanks for the reassurement Paradox, that's a lovely set up that you've got there!

From a heat perspective, with these LEDs if they're more than 1 inch away, heat is a non issue.

Distance seems important to allow the colours of light to merge, and also so that the light isn't too intense so as to burn the leaves.

Hopefully this will be fine as you say

I somehow missed that they were LED. So yes heat shouldnt be a problem.

 

[JudyB]

Here is my winter setup for my tropicals:

Nice rain trees Sandy!

 

[Paradox]

Nice rain trees Sandy!

Thank you

 

[MrFancyPlants]

This is a 50 watt led chip. believe it or not, the ficus loved it in there.

 

[Whitefall]

This is a 50 watt led chip. believe it or not, the ficus loved it in there.

Wow! I love that you're growing a tree there

It looks very close to the bulb. I wonder if it works out well because it's not a red/blue light like the one that I linked, I think the grow light needs distance for the lights to merge and is a bit intense from a UV/IR point of view. I'd love someone to enlighten me on this a little more

 

[milehigh_7]

I always say the closest you can get without too much heat is a lovely mark to shoot for. You are very likely not going to get them too much light indoors. Burn on leaves outside is not from the heat it's from the UV. You won't have that problem with regular bulbs. the 50W lamps do build up some heat so make sure you have a fan moving the air out from under the hood.

 

[milehigh_7]

Oh nvm I did not look at your picture... Never worked with those. Mine are 50 W HO fluorescents

 

[Whitefall]

Oh nvm I did not look at your picture... Never worked with those. Mine are 50 W HO fluorescents

No worries, I haven't quite figured out how to get a photo to show up embedded within my post yet.

Yeah these things are a bit different, most of the LEDs are red and blue, then some white and some UV. The room is bathed in purple light whilst they're on.

Am I going to do much harm only having the lights on Mon-Fri whilst I'm at work? I guess it could be quite confusing for the tree but I'm not sure what harm would be done? The reason being that I don't have a dedicated grow room and I'd probably need to walk around with sunglasses on with these things

 

[sorce]

photo

PC...drag and drop in reply box.
Phone...hit the upload photo tab.

.....

Get the sunglasses!
I'd leave em on!

I found a lot of info googling light spread.
Seems ten inches is good.
But the manufacturer should give specs.

One review said two inches.

Sorce

 

[Whitefall]

Can anyone recommend some E27 bulbs that I could change these grow lights out for on the weekends please?

Something that wouldn't be damaging to my eyes when in the room, it doesn't have to be optimal (the grow lights can take care of that in the week). Just something that would be beneficial vs my north facing window.

 

[ysrgrathe]

Some things to note, mainly for others that might read this thread.
1. This isn't a 50w light -- it is really about 15w. The marketing is confusing!
2. It's better to look at light output -- lumens, or even better PAR. This light is cheap, but don't spend a lot on LEDs that don't have a PAR rating.
3. This light is 2500 lumens. That's OK if it is 1-2 plants super close but it isn't a ton of light; my 4' 4 T5 HO florescent is around 20,000 (it's also much bigger though so the light is spread out more).
4. You can use your phone as a light sensor. It isn't nearly as accurate as a PAR meter but it can give you an idea of how bright the light is. I use the beecam light meter.
5. For comparison my T5 setup is around 15,000 lux close to the lights, an eight bulb gets to 28,000. Full sun is 50-120,000.

 

[Leo in N E Illinois]

Full sun is over 9000 foot candles of light. I believe that is roughly 10,000 lumens. Actually unit of measure would be lux, lumens per meter square. Even 400 Watt high pressure metal halide, and or high pressure sodium lamps don't deliver that at a distance cool enough for plants to survive (24 inches with fan) . Point being you won't have to worry about LED being too bright.

I tried and discarded LED systems several times. First in 2004. Again 2008. Both times output was too weak, growth was inferior. My 2014 venture failed due to crappy quality control. Three times unit failed to light right out the box, or failed within 48 hours. Vendor kept replacing at no cost, eventually got my money back.

Light output has improved nicely, new 2016 or newer units can put out enough to quality for about 25 to 40% of direct sun, good enough to grow a wide variety of things. Color is a real issue, it is disorienting to see in just blue and red. The new white LEDs are better.

By the way, the colors in autumn leaves, the reds, yellows, etc. Turns out they capture light also, and then pass either a red wavelength photon off to the chlorophyll, or an electron to the cytosome series (chlorophyll works by passing an electron to the cytosome series) meaning plants do use more of the spectrum than previously thought. White daylight is best, both for aesthetics and to utilize the full growth potential of the plants.

 

[GrimLore]

I use the beecam light meter

Looks like a pretty cool app! Adding it today and will compare results to inexpensive meters

Grimmy

 

[Whitefall]

Thank you both, that was very enlightening to read.

I guess that I really don't need to worry about how close these LEDs get, they're not going to get anywhere near being too bright.

At this point I think I've done about as much as I can in my environment. I'll just have to see how this set up goes for a couple of months (2* 2500 lumen bulbs at 10" away from 2 trees). If the trees don't do very well then I guess I'll have to forgoe trying to grow bonsai until I move house/have a garden.

If anyone has any newer white LEDs that they'd like to recommend then I welcome that please bear in mind that I'm in an apartment and using my living quarters as a grow room whilst I'm at work. This is why table lamp set ups are more appropriate than lights that hang from the ceiling/more permanent structures.

Thanks,
Whitefall

 

[Rambles]

2. It's better to look at light output -- lumens, or even better PAR. This light is cheap, but don't spend a lot on LEDs that don't have a PAR rating

This isn't correct. PAR is a measurement of the physical dimensions of the bulb and (unlike R or BR bulbs) comes in flood, spot, and narrow spot varieties.

 

[ysrgrathe]

There are a lot of overlapping three letter acronyms. This one is photosynthetically active radiation and is the primary way professionals and academics think about light in agriculture.

https://en.m.wikipedia.org/wiki/Photosynthetically_active_radiation

 

[Rambles]

There are a lot of overlapping three letter acronyms. This one is photosynthetically active radiation and is the primary way professionals and academics think about light in agriculture.

https://en.m.wikipedia.org/wiki/Photosynthetically_active_radiation

I humbly stand corrected and have learned something. Thank you.

Though I suspect anyone shopping for a bulb in person would run into the same ignorance when asking for a bulb. Seems like a different TLA would have been a good idea, but what can you do, eh?