Light supplement for seedlings

[Yéri]

Hey everyone,

I have a small greenhouse (actually a part of the sunporch closed off from the rest) to grow my orchids in.

I get medium amount of light and humidity stays around 60% during winter as I have central heating in the greenhouse and the air dries out more easily.

I have about 50-60 seedlings I think, I tried out deflasking etc. last year and well...moderate success.

I feel the light and humidity are a bit too low for my seedlings to be healthy, so I thought of adding a miniature greenhouse inside my actual greenhouse.
This is it the model, mine is smaller houten kweekkas zonder verzendkosten - kweekkas te koop van hout - houten kweekkas

Of course, I could keep my seedlings with higher humidity with a fogger in there, but the lighting will be lower in there because of the extra layer of polycarbonate...

So I was thinking of using these LED tubes in order to supplement some lighting:
60cm 10W 140° radius 1022 lumen 5700K

Would 1 be sufficient to supplement lighting on a 30cmx60cm area? I was thinking of hanging the tubes at 20ish cm off the plants.

Also, as you can see there are several layers on which I'm going to put my seedlings. Would the bottom part require significantly more lighting?

I'm happy to hear any comments you have on this project.
Alternatives are always welcome, but I found these LED tubes at 25€ (with starter) and consider them the best option regarding price and energy savings.

[WhiteRabbit]

[Yéri]

Well thank you for the bump! But I understand my situation is a bit complex and my question not too easy to answer.
At least that's what I feel after reading (even) more about it...

So let's leave out some factors and assign numbers to the questions. Just answer what you feel like!

Let's say I have a basement and I want to have reasonably efficient grow lights. I'm not looking for theeeee best setup, just something that would make sure they're healthy and reasonably growth

1) How many of these LED tubes would I need for a 30x60 cm area: 60cm/10W/140° radius/1022 lumen/5700K

2) Regardless of any other factors, would these LED tubes be more effective: 60cm/8W/800 lumen/6500K/Daylight spectrum

3) Is it true the spectrum of the light is more important than lumen for growing orchids?

I'm sorry for these questions, I know they must be coming from all corners. But I'm just trying to figure it out and no matter how much I read about it, it keeps getting more confused!

Any advice is welcome!

Yéri

[naoki]

Originally Posted by Yéri

1) How many of these LED tubes would I need for a 30x60 cm area: 60cm/10W/140° radius/1022 lumen/5700K

I'm using 4x 9.5W household LED (Cree 3x warm/soft white + 1x daylight white) to cover 60x60cm area since last summer/fall. 20-30cm above the leaves with reflector made out of aluminum beer cans. They are relatively low light plants (Phal and Paph species), I feel that they might do better if I give more light, but they are growing ok. So 2 bulbs might be a good start for your area. For the first year or 6 months of the deflasking, I try to use a little lower light.

Originally Posted by Yéri

2) Regardless of any other factors, would these LED tubes be more effective: 60cm/8W/800 lumen/6500K/Daylight spectrum

You say LED "tubes" (not bulbs). Are these the one which looks like T8? Both of them seems to be more efficient than the household LED bulbs in the US. Who makes them? With regard to 6500k vs 5700k, it probably doesn't matter. If you are interested in the comparison of different types of white, take a look at the third link of
LED related links
I personally use warmer (around 3000K) white LEDs now, but I don't have a strong justification for it. Bluer white LED may be more efficient in terms of photons/W since all recent white LEDs are blue emitter + phosphor coating. But the emission spectra of warmer white LEDs contains more efficient spectrum in terms of photosynthesis (see Table 1, YPF/PPF row of the poster I mentioned above).

Originally Posted by Yéri

3) Is it true the spectrum of the light is more important than lumen for growing orchids?

Intensity of light is important, but lux/fc/lumen is not a perfect to measure the intensity that plant experiences (PPF(D) is a bit better index):
http://www.gpnmag.com/sites/default/...13%20FINAL.pdf

But if you are using whitish light, you can approximately use lumen, lux, fc, which is influenced strongly by the intensity of green light.

[Yéri]

Wow that is a ton of information to process! Wonderful!

I know what to do tomorrow afternoon

I will get back to you once I've read all of that. Your explanation answered my questions and cleared up certain things...but raised another set of questions of course!

Thank you so much for the help, it's just not easy knowing where to start and how to work your way up to understanding the whole thing...

[Yéri]

Okay so I read the links you provided me and tried to make sense of it.
The first one was really interesting for the table 1 as you said. I tried understanding the whole publication, which went...not as well as just looking at the YPF line and looking at the different yields.

The second article was not complicated at all, but as I'm just buying regular T8 LED tubes, I don't think it's that relevant for me.

Unfortunately, I would love to calculate all this, but my budget is limited and these are my most interesting options:

1) LED TL-lamp*LED TL-lamp 60cm 10W met starter

As we are dealing with limited information and white LEDs, I will be using the amount of lumens as an argument (200 more than the T8 bulb below).

2) Led TL 60cm cool white (6500K) - EcoBright
This one is again just from a regular webshop, so limited information as well. It seems I'll have a more efficient light spectrum, plus 6500K seems better for pure growth (seedlings).

I can't come up with a concrete conclusion, but I feel like light efficiency from the second one might be what I prefer...

I'll just go and look for a DIY TL-fitting for LED T8 and start my shopping!

Feel free to comment of course, any help or recommandations are welcome!

Best regards

Yéri

[naoki]

Well, Yeri, the 2nd article is basically related to a part of your question about how the spectrum can influence photosynthetic efficiency. It is super basic, but some people don't know the limitation of using photometric indices for plants.

I don't have any experience with the particular models you are talking about. But the 2nd one looks like that it is using old fashioned 3mm DIP LEDs. These are not really efficient with the current standard. Probably florescent light is better.

I might be wrong, but I'm pretty skeptical that they can get really 800 lumen out of 8W. Even Cree of Phillips household LED bulbs, which use more modern emitters, can't achieve that level of performance. I have similar 60cm T8 style LEDs from ebay, but mine is red-blue type. It was advertised to use 8W, but it only uses about 4W when I measured it. And it is pretty dim (compared with other old R+B grow light with 10mm DIP LED, whose max capacity is about 0.5W each). You can use it, but you'll need to have quite a lot of these bulbs, and it's not cost effective (T8 is probably better than this). For the first one, I can't see what kinds of emitters it is using, so it might be a better one.

As a side note, with LEDs, you need to be careful with the advertised specs. For example, many makers list maximum capacity of the emitter as the wattage. For example, if they use 10x diodes which is capable to run at 1W each, then they may say it is a 10W fixture. However, most of them drive the LEDs at much lower current (1/2 to 2/3 of the max seems to be common) than the maximum capacity (generally this increases the efficiency, lumen/W, and longevity). So the 10W fixture may be actually 5W unit. With household bulbs (the type which replaces CFL), they seems to list the actual energy consumption.

[Yéri]

Again, thank you for all the information.

Everything you say makes sense to me, but I would really like to stick to LEDs because of the longevity and reduced energy cost.

I've come to realise (finally you will say), that simple cheap TL won't really be efficient and am moving away from those.

I've been looking into CFL LEDs and stumbled upon something that might do the trick for me.
15W LED = 60W CFL or 12W LED = 45w E27 PAR38 Bulb Grow Light Lamp Blue Red White | eBay

I don't know how much of this is (or isn't) false advertising, but the specs look way more plant growth related.

Thanks to one of your links, the 0.97 PF caught my eye. I think they mean YPF/PPF for this value, right?

The only thing I'm missing here, is the radius (°) each bulb would cover. They say the directional lens will keep all the light going downwards, which I interpret as having a smaller radius...
So I'm not really sure how many I would need for a 30x60cm area.

If you have the courage and patience to help me out once again, I would very much appreciate it!

Best regards

Yéri

[naoki]

Yeri, the longevity and reduced energy cost could be a bit hyped up. For example, if you get a low quality LEDs, the diodes could die. With my crappy grow light, I had to replace a couple diodes within a year (fortunately it was easy to desolder/solder them). With energy saving, it is pretty difficult to come up with a number backed by data. One of the link in my thread has the comparison with HPS. It is interesting the efficiency of LED is all over, and it has to be a well designed fixture to be efficient. I put really rough comparison of LED vs CFL in this thread. Saving may be about 20% over CFL, but linear florescent light is more efficient than CFLs.

I think there is a member who successfully uses this types of screw-in PAR LEDs from ebay. The bulbs are using 1W-class LEDs (should be better than 3mm DIP LEDs), and the actual wattage is probably lower than 15W (maybe 7-10W?). I'm guessing that 2-3 will be a good start for your area (what kind of orchids are you growing?).

Have you considered this type?

But now I'm wondering where you are going to put the light (inside or outside of the enclosure). With a small enclosure, you have to worry about the heat. Also if you are putting them inside, then the beam angle become an issue as you mentioned.

I don't know what 0.97 PF means in the link.

[Yéri]

Hi Naoki,

I'm growing all kinds of seedlings at the moment. Let's see...
Baptistonia echinata
Dimorphorchis lowii
Pleuro's
Platysteles
Dendrobiums
Scaphyglottis
Oncidium
Oerstedella centradenia
Barkeria melanocaulon
Bulbophyllum
And more...

So there's all types of light requirements, I know, but I can play with heights/amount of bulbs if I'm having a level of plants with low light requirements. It's more about finding some type of correct lighting for plants.

The lighting would be completely inside the enclosure, I can give it a max of 27cm off the plants per level, not more (but I can go for less) as I can move the shelves.

Depending on the heat the lighting gives, I can play with the ventilation/humidty. My greenhouse itself (where the enclosure will be in) is well ventilated.
I can always add fans for extracting the excess heat.

The type of lighting you linked to seems totally different from what I've seen so far. I can see the radius would be perfect (?) at 120° on those and of course waterproof means I wouldn't have to worry about watering the plants...

Is this something you would recommend, taking into account my preferences? Apart from the abovementioned, (radius, waterproof) I don't see a lot of differences except for the design.
Probably you are more familiar to this type of lighting.

Although I'll have to research about RGB with 24 keys IR controle

As always, thank you for the time you're putting into this. I feel like I'm getting somewhere with this!

Best regards

Yéri