lighting

I have been considering extra lighting to start things off earlier. I have been looking at lighting kits and many seem to resemble my incubation lights.

Would it work to use these light shades with the broadspectrum light bulbs?

It would save a considerable amount on the cost of setting it up!

 

Hi Waco,

Normal lamps produce mostly heat and very little useful light that plants can use (PAR).
Compact fluorescent lamps, and tubes in banks can be useful for seedlings and small plants.
Cool white is good for blue spectrum (leafy growth) and warm white for the red spectrum (flowering).
A mix of both types is best, usually with a ratio of 2 cool to one warm.

To cover the entire greenhouse area with just a few lamps you`d need high intensity discharge lighting, metal halide or high pressure sodium.

Your greenhouse would become a lighthouse at that point :D

 

Hi Waco. I put a few comments on this subject on this thread. http://www.gardenerscorner.co.uk/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=002626

It seems clear from the American "growing under lights" forum that you can use ordinary fluorescent lamps. But to get a good effect you need a pretty high intensity of light. To get the best value for money, you need to use "light insulation" in a similar way to heat insulation. ie you need to prevent light going to waste, by using efficient reflectors, and perhaps surrounded by reflective walls. Any light that you can see is wasted light.

 

Just to add to what Peter has said you need to be very close to the lights to get the full benefit and you then have to be careful of scorching ,I have a moisture/light meter that measures light intensity and even a matter of inches away from the light makes a big difference to the light reading you can never beat natural light even on a dull day

 

Thanks all - loads of good material to consider.

 

Walnut - I have been thinking of doing something like this myself. What sort of light level reading should you be trying to achieve.

 

Peter the light meter I have is scaled 1to10 one is obviously dark never had the light strong enough to reach the ten I usually aim to get the light level to five or six I find you get good growth at that measure.
http://cgi.ebay.co.uk/PH-MOISTURE-LIGHT-METER-SOIL-IRRIGATION-WATERING-ET1_W0QQitemZ180089229123QQihZ008QQcategoryZ139909QQrdZ1QQcmdZViewItem

 

Waco - have just worked out what you are trying to do - there's some info here on lights http://www.skunked.co.uk/articles/growing-marijuana-03.htm

 

I have delved a bit - and come up with a few facts. Total light is measured in Lumens. The more Lumens you get per watt of power, the more efficient is your bulb. Typical efficiencies in Lumens per watt are as follows though there is a range of values for each type:-

Tungsten (ordinary light bulb) 20
LED (new type of torch) 50
Linear fluorescent (office lighting) 83
HPS (high pressure sodium) 100
LPS (low pressure sodium - street lamps) 150

A typical 4 foot fluorescent tube will be 36 watts and so give out 3,000 Lumens (36x83).

Light density is measured in Lux, where a Lux is one Lumen per square meter. Typical densities are :-
0.00005 lux = Starlight
1 lux = Moonlight
10 lux = Candle at a distance of 1 ft
400 lux = A brightly lit office
400 lux = Sunrise or sunset on a clear day.
1000 lux = Typical TV studio lighting
32000 lux = Sunlight on an average day (min.)
100000 lux = Sunlight on an average day (max.)

You should aim for a light level of 2000 Lux or more. Thats still only about 1/25th of average sunlight. If you could concentrate all the output from a 4 foot tube ie 3000 lumens onto an area of 1 square meter you would have 3000 Lux - ie enough light. But even if the tube is only 2 inches away from your plants, only a small portion of the total light given out will fall on the plants, as most will go out upwards or sideways.

Conclusion - you need a lot of light. Reflecting stray light onto the plants is most important.

 

Oh you are so funny Peter! but I never needed marajuana to make me waco - it always came naturally!

When I pass Rogers nursery, they have these things that look like my old brooder light - a piece of aluminium made into an ark with two 200wat light bulbs underneath. I just think if I replaced these bulbs with the white light bulbs it may do some good.

Having said that, I went into rogers yesterday and - oh dear the state of their glass house, just streaming with rain from the constant downpours we are getting. I think they may be buying much of their stuff in now - but I digress, I can see myself selling them all walnuts Bruggies that are invading me in near distant years .........no of course I would not part with them - well of course only back to you walnut if you lost your stock.

 

Waco - there was a serious point to that reference. The people who grow marijuana are actually very skilled at growig things under lights. Their plants often never see daylight - so they have to be getting it right. I think we could learn a lot from them.

Walnut - thanks for your info about the light meter - that is remarkably good value. It also encouraged me to go looking for a bit more information on what levels of light we should be striving to achieve. I keep coming back to the fact that it will be a struggle to get enough light without incurring huge costs.

I also came across this site, which shed a little more light on the subject. http://www.weblightmeter.com/index.php

 

Actually the police look out for growing lights at night time when doing their patrols in the helicopter they have caught a few cannabis growers the glare of their lights has given them away
Waco you aint seen nothing yet :D

 

Just to point out that 220/240v AC in a greenhouse (think bath or shower then add some) is a killer. You MUST get professional and qualified electricians to do the job. 12v or 24v isolation with an earthed centre tapped transformer installed indoors is much safer and you can use 20w or 50w halogen spots for a small propagator.You do need heavy duty low voltage lighting cable though as the current is much higher. It is nice to have at least a small light installed in a greenhouse

The really cost effective way to add lighting for plants is to use old reclaimed mirrors to reflect light back onto your plants or even a piece of stategically placed kitchen roll with some support canes. Be wary of full sun though as even on a spring day you can scorch plants if you create a focus point on them.

 

Thanks - very informative thread here. Peter - we live in North Yorkshire - we don't know what police are! take your point though which reminds me, I must get my calladiums out of the airing cupboard.

Frogesque -Martins best friend is an electrician and keeps us on the straight and narrow, but a very timely warning.

 

Thanks Waco, not trying to teach anyone to suck eggs but I've seen outside lighting done with twin cable passed through a hole drilled in an alluminium window frame. Bad enough but the indoor plug had a bit of wire wrapped round the fuse :eek: