Growlights: Building the Perfect Grow-Box

Freddy - that sounds like loads of light and heat and you should do well. Though I must admit that I am not a grower of onions and don't know what their requirements are.

 

I put my Onion seedling trays under my grow-lamp last Spring, to bring them on a bit, and then I woke up one night in a cold sweat!! remembering that Onions bulbing up is triggered by day-length (I run my supplemental lighting at night, so the seedlings had sunlight during the day too) ... so I decided to move them away from the supplemental light. No idea if it made any difference as although the Onions were not brilliant this year, the weather was rubbish too ...

But it might be something worth considering / researching further

 

Hiya folks, thanks for that.

Kristen, I'd kinda got it in my head that maybe I should use the lighting to supplement(and possibly extend?)daylight given the low light levels during winter. What do you reckon?

 

I think its a good idea, my seedlings, those that have supplemental lighting, are more stocky and more advanced than those that don't.

My recollection is that Onions start bulbing up when the daylight starts to shorten - so my worry was that if you give than 8 hours (say) Sun and 8 hours (say) supplemental light that the moment you then stick them outside they think they have gone from 16 hours daylight to 8!

But I'm sure someone on an onion growers forum can put your right on that. I have no doubt that supplemental light will produce better plants, come May.

 

Hiya Kristen.

I've just re-read my posting and your subsequent reply. I'm not sure if we're talking at cross purposes? Just to clarify.... I plan to use the lighting DURING the hours of daylight, and maybe extend the daylight hours by an hour or two, probably no more than that.

 

Can't see a problem with that

I don't do that because it seems expensive to me - My route is to use the sun when it is out, and pay for electricity as a supplement (i.e. at night).

In Winter I guess the Sun isn't much use, even when it is out.

 

My understanding is that CFLs are the same as T5s, but in a different configuration - all coiled up rather than spread out.

So what's the difference between 4 x 125 watt CFLs with reflector for £100 http://www.3ch.co.uk/grow-lights/fl...-cfl-125watt-reflector-package/prod_1231.html and these T5 lights at around the same cost http://www.3ch.co.uk/grow-lights/fluorescent-grow-lights/t5-4-tube-long/prod_843.html or more specifically this one I have just bought http://www.3ch.co.uk/grow-lights/fluorescent-grow-lights/t5-8-tube-long/prod_829.html

If the CFL version of tubular lights presents a more intense light/m2, then what makes that an advantage?

 

Freddy - there is not much difference between 100 watts worth of tube or CFL - they are both fluorescent tubes.

Technically, I have read that the CFL's give out slightly less light - its to do with the inefficiencies of the tube ends - the more ends the more inefficiency. I have tubes and they give out a nice even light.

Frankly, I would get something that was convenient in terms of dimensions, and the quality of the built in reflectors. If you have a point source, ie just a bare bulb, the light falls off quickly with distance (inverse square law). But if you have tubes or a light with a reflector it doesn't apply. Think of a WWII searchlight. The reflector makes the beam nearly parallel, and consequently the light hardly falls away with distance at all, and you can illuminate an aircraft 25,000 feet away. So a good reflector could clinch it.

 

Whenever I look at those bulbs the thought occurs to me that half of the light must travel into the centre of the bulb, rather than directly down onto the plant, or up, and reflected back by the reflector.

I guess that can't be the case or they would be only half as efficient as T5's though???

 

Actually Kristen, you are right - they aren't as efficient.

I have had a quick look and can't find a good source of info now. But when I was doing some research for my lightbox, I came across an American forum, where they said that in Europe CFL's were quoted as 5 times as efficient as incandescent lamps - similar to fluorescent tubes. But that in the USA, by law, they were only allowed to quote a figure of about 3.5 to 4, because they weren't as efficient.

I have a CFL in front of me where they say 11 watts is equivalent to 60 watts of incandescent (ie x 5.5). If you use the American 3.5 - that equivalent to 39 watts. No wonder everyone says CFLs are not as bright as the old bulbs.

 

I might buy one and try side-by-side with my shiny new (as yet unused ) light meter

 

I see some of these new CFLs have started to quote output in Lumens rather than the equivalent incandescent bulb. This is an improvement - except that no one understands lumens.

One of the problems with any comparison is the reflector, even if its only the fitting which isn't designed to reflect - but will reflect something. As I said above there is a huge difference between a bare bulb and a searchlight. This is why I made a lightbox, with a reflecting top and reflecting closed sides - it is much closer to the searchlight set up than just a bare bulb.

When I was making my box, I found some nice CFL's with a very shiny reflector in sealed glass - like a headlight. I originally planned to use these, but I quickly realised that I would probably never see them on sale again - and I haven't. So I altered the design to tubes.

There is an advantage with CFLs in that, when a bulb dies, you can easily replace it. Its more complicated with tubes. I have already had several go. My original tubes had ballasts - not starters and two out of the three ballasts have gone. Homebase, where I bought them, never stocked the ballasts and no longer stock the same fittings, nor does anyone else. So when the first one went I had to replace the whole fitting with a different type. But the second time I bought a ballast on the internet, however it was different to the original so I had to do some rewiring. What could be a problem with a specially made array of lights is how you replace one that is not working. Replacing tubes or starters is easy, but replacing the whole tube unit could be more of a problem.

 

Thanks, you've alerted me to the need to buy some "spares" for the T5 rig
I bought recently. Should have bought them together with the kit to save carriage :(

 

My grow cabinet is ready, and I plan to deploy it by next weekend. Its total power consumption will be 30 Watts. 15 Watts for the large heat mat that is on the germination shelf, and 15 Watts for the LED array grow light.

I have no experience at all when it comes to artificially tricking a seed/plant to believe ist spring rather than winter, so my project might be a complete flop, but its going to be fun, and even if it fails, it wont have been a waste of time because we learn at least as much from our failures as we do from our successes.

 

Good for you Clueless. You will find it fun - and, as you say, we all learn from everything we do.