How long to light my propagator

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Andy J

How long to light my propagator

Post by Andy J »

Well my prop is now fully up and running with heat and light. As i am running the 200W lights at night on cheaper electric i need to decide on how long is enough. The cheap rate leccy is about 7 hours i think and this wont be long enough. I was thinking about 12 hrs,say from 7 till 7 or something. it is near to the patio doors so does get some light during the day but nowhere near enough. What do you think?
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helen
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Re: How long to light my propagator

Post by helen »

I light mine 18 hours a day
Be careful, it's a jungle out there!
Andy J

Re: How long to light my propagator

Post by Andy J »

Wow! more than i thought then. I suppose in high summer we must get about that many hours daylight yet in nearer the equator arent the day lengths more uniform throughout the year at around 12-14 hours? To be honest i will do what i need to to get good results.
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Chad
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Re: How long to light my propagator

Post by Chad »

I light mine for 12 hours a day. Anything that is photoperiod sensitive will be very confused if it doesn't get 8 [ish] hours of proper darkness, so I'm not sure how it would work 'out of synch' with day light, if that can still get in.

Chad.
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helen
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Re: How long to light my propagator

Post by helen »

Got my '18 hours per day' from a hydroponics shop. Plants seem to cope ok with it.
Be careful, it's a jungle out there!
Gaz

Re: How long to light my propagator

Post by Gaz »

what do you light it with? :idea:
im thinking of rigging something up in our outhouse for next winter so any suggestions helpful.
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Chad
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Re: How long to light my propagator

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John Jearrard

Re: How long to light my propagator

Post by John Jearrard »

It depends what you are trying to achieve. If you want to promote photosynthesis, then 200w of light will have an effect. I wouldn't personally bother with more than 12 hrs a day as a maximum, assuming you are just trying to keep things ticking over in good condition until a decent growing season arrives.

Make sure your other growing conditions are good (feed, water, temperature etc). Plants work on a 'limiting factor' principle. The commonest limiting factor in winter is low water levels. People keep their plants dryer. If there is insufficient water for active growth then you can use all the light you like, it will just be wasted. If light is actually the limiting factor, then 7 hrs of cheap light is a very great deal better than none.

If you are trying to convince plants that it is still a long day growing season, then you do not need very much light at all. A 30w incandescent bulb will be plenty (it doesn't even need to be very close to the plants - one bulb in the same room would be enough). The cheapest way to produce long days is to use it as a night break. One hour of light in the middle of the dark period ("night") will be enough to split the dark period into two. Plants do not measure daylength, they measure nightlength. If you reduce the night to two eight hour periods, the plant registers it as two 'eight-hour-night' (ie 16 hour day) days, and it behaves accordingly.
You have to use an incandescent bulb - you need light in the red and far red part of the spectrum to influence the particular photochemical 'switch' involved - fluorescent tubes, sodium lights, high pressure mercury etc are too pure, and don't contain the red colour needed.
This is why Dahlias dont keep flowering all winter in gardens lit by sodium street lights - the yellow light doesn't influence the photochemical switch!(Well, that and the frost!)
Ooops - I've gone on a bit!
Andy J

Re: How long to light my propagator

Post by Andy J »

I am using an Envirolite 200w in a closed case with a digitally controlled heat source currently set at 80f. I am really pleased with the light output and it emits enough heat to negate the need for any supplementary heating while it is lit. I am looking to give ideal growing conditions for the early starting of seeds and plants with a view to extending the growing season by a few weeks. I have canna seedlings in there at the moment which seem fine but its still early days as the system has only been running since the weekend. I am planning on putting some ricinus seeds in there by the end of the month too.

I know what you mean about the photoperiod thing, i used to get my Poinsettia to flower every year in time for xmas by keeping it in the greenhouse where the shortening day length needed to induce flowering was met when people who kept them indoors and under lights just got green leaves. Its the same thing for Chrysanthamums as well. I did either read or see on tv,cant remember now! a thing where they kept plants under bring lighting for 24 hours a day to see if they grew quicker and although they did it wasnt greatly so.

Anyway, back to the original question now,i will try around 12 hours a day for a week and see if thats enough,if not i will extend it by an hour a week and by that time it will be spring anyway and i wont need the lights then!!! :lol:
nicebutdim
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Re: How long to light my propagator

Post by nicebutdim »

Andy J wrote:Well my prop is now fully up and running with heat and light. As i am running the 200W lights at night on cheaper electric i need to decide on how long is enough. The cheap rate leccy is about 7 hours i think and this wont be long enough. I was thinking about 12 hrs,say from 7 till 7 or something. it is near to the patio doors so does get some light during the day but nowhere near enough. What do you think?
Last winter I ran a metal halide light above my propogator for between 8 and 18 hours a day and saw no difference,the light was about 2 feet above the propogator.All I achieved was a ticking over of the small alocasias I was trying to bring on. The temp was around 80 F , not sure what that is in real money.What little success I had, was instantly reversed when the spurt of growth of the corms was taken out of the propogator,even though they were acclimatized gradually,all this was done indoors.I moved on to a "cheaper lighting method" i.e. low voltage,what I didn't realise however was that low voltage does not mean low running costs.Low voltage of 12v which seems to be standard needs a higher wattage to give the same light output, so 4 x 100 watt ordinary lights bulbs cost the same to run as 8x50watt halogen lights(it seems 50w is the highest available.) I read somwhere that a plant can detect a light change in duration of 15 mins!
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Re: How long to light my propagator

Post by Dave Brown »

nicebutdim wrote:I moved on to a "cheaper lighting method" i.e. low voltage,what I didn't realise however was that low voltage does not mean low running costs.Low voltage of 12v which seems to be standard needs a higher wattage to give the same light output, so 4 x 100 watt ordinary lights bulbs cost the same to run as 8x50watt halogen lights(it seems 50w is the highest available.) I read somwhere that a plant can detect a light change in duration of 15 mins!
In terms of electricity cost watts is watts = Power. if you use Ohms law volts x current (amps) = Power (watts). Watts are what you pay for so 4 x 100w =400w also 8 x 50w = 400w. The voltage makes no difference. As you lower the voltage you have to increase the current to give the same Power (watts). :wink: Probably as clear as mud :lol:

What you need to lower your bills are low energy bulbs, but I'm not sure how well these work with plant growth. :DD
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Dave
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grub

Re: How long to light my propagator

Post by grub »

i must admit i've been reading about lighting and thinking, 200W you gotta be joking :shock: . surely you can light the plants using flourescent tubes, in holland aquarists keep aquariums more for plants than fish, a by-product being the availability of tubes with different spectrum ranges to encourage plant growth, visit your local aquarium supplies shop and have a look :>beard<:
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helen
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Re: How long to light my propagator

Post by helen »

Grub, we are talking fluorescents here. Envirolites are compact fluorescents. Andy runs 200W fluorescents, I run 125W fluorescents.
Be careful, it's a jungle out there!
grub

Re: How long to light my propagator

Post by grub »

o.k i see :oops:, i knew they were compact lamps and having seen halide and mercury lamps mentioned somewhere thought that was these. its because i'm always trying to do everything on the cheap :idea: i thought flourescent fitting 5ft £15 and 58W lamp £15 has to be cheaper
Andy J

Re: How long to light my propagator

Post by Andy J »

Grub, i ran a 4ft planted tank some years ago,correct substrate,CO2 injection,everything. I looked into correct lighting then amd i ended up with 4 40w tubes =160w and this was only just enough to provide adequate lighting yet still not enough for high light species such as tropical water lillies. Therefore i am happy that 200w is what i need. That said i think Helen and her 125w is fine too. If you think that you can look at a flourescent light and not have to shade your eyes yet if you look at the sun it damn well hurts! (please dont try this at home!) That will give some idea of the difference in light intensity. Also without getting too boring,tubes sold for home use are totally the wrong colour temperature for photosynthesis. I personally would rather use a 200w tube designed for plants than 200w of home use tubes to do the same job. You would be wasting power on providing the wrong sort of light,a bit like the wrong type of leaves on the railways i suppose!
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