Allotment Gardening Advice Help Chat
Growing => Growing in Greenhouses & Polytunnels => Topic started by: adri123 on December 04, 2014, 09:44
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Hi
I'm finishing off a cedar greenhouse to supply seedlings to our polytunnel.
I have the chance of power in there and will be installing some growlights I used in our house last year. I'll also have a frost protection heater in there.
What would you sow/grow now? And later?
TIA
Adri
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If I may ask - how are you going to protect yourself against condensated electrics?
I was once cleaning a fan in a swimming pool room which had high humidity and got quite a shock off that. My polytunnel gets quite wet and so has put me off electrics in there.
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It's a good question....errrrrrrmmmmm...
I suppose to start off with I'll control humidity and see how it goes. What I won't do is pick up a wet electrical item....
Adri
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My thoughts before now has been a weatherproof electrical box within another box sited outside the polytunnel with rcd electrics being switched and fed off that.
Trust me, from experience, you won't always know your electrics are wet until you touch them.
I do plan to ask some professionals on this matter.
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Is if safe to assume that a Greenhouse fan heater (i.e. sold for the purpose) has suitable insulation rating for a "wet" location?
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I'd always have such a setup on an RCD. I think that would make it safe enough.
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@ Kristen - I honestly don't know. I would suspect it would depend on its IP rating and whether it was double insulated. Some people are very good at keeping their space well ventilated and others are not - like me - and it does get wet.
@Adri - I'm tempted to agree. The caveat being the fan in the swimming pool room was rcd and I still got a shock.
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Some people are very good at keeping their space well ventilated and others are not - like me - and it does get wet.
Maybe depends more on how stuffed your greenhouse is? and shading-casting trees etc.
I have found that running a fan in winter, in a frost-free greenhouse / conservatory, dramatically reduces rot; my experiment in successive years was high levels of rot with no fan in a relatively dry winter, and zero rot the following winter, with fan, in one of the wettest winters on record. I run the fan on a segment timer 15-on and 45-off.
However, this is for over wintering plants that are not hardy outside, rather than raising veg etc., so may not be entirely relevant.
I expect that damp / rot may be worse in bubblewrap insulated structures - more air-tight / less draughts to replace air - and perhaps more worthwhile there? Old fashioned use of Paraffin heaters, which generate a lot of condensation, used to be accompanied with providing a decent amount of ventilation too - Paraffin was relativity cheap back then!
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Kristen - an extremely valuable reply there - *thank you*. I will be utterly certain to do this asap.
So much so, I would urge the mods and admin to include this tid-bit in the general knowledge section of maintaining an enclosed grow-space (please!).
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I am with Kristen on this. Amongst other things I exhibit Pelargoniums at a couple of local shows so have a few of them to over winter. My fan is on a timer during the day, one hour on, one hour off. At night I leave it to the Fan Heater which switches on at 6c. I never get any rots or moulds and thats with my Greenhouse sealed as tight as a drum with bubblewrap.
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An RCD will not stop you from getting a shock, It will limit the one you get!!
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You only need the RCD for 240v stuff.
In my greenhouse I run a 12v 20cm/8" fan with a 4v min directly from a solar panel. The brighter it is the faster it spins. Humidity control is an air movement issue
As for the grow lights in a greenhouse I can see thier use in darker weather but they'll also block a lot of free natural sunlight later n the year
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As for the grow lights in a greenhouse I can see thier use in darker weather but they'll also block a lot of free natural sunlight later n the year
Using a lamp, rather than a lighting-rig, doesn't block much natural light. For example Metal Halide is high powered, so cannot be placed very near the plants (at least 2' away), and just has a reflector. I guess that if having them as supplemental lighting it might be worth having the higher wattage ones? Mine is 400W and lights an area about 1m square. A 1000W bulb would light a larger area, but still have the same sized reflector.
I used mine in a small polytunnel, placed within my conservatory, and run overnight - the waste heat from the bulb meant that I didn't need a heater and any additional natural light the plants got during the day was a bonus :)
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400w, let alone 1000w is a lot of power!!
You're not growing those funny green plants are you :lol:
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400w, let alone 1000w is a lot of power!!
You're not growing those funny green plants are you :lol:
:) No, but ... the Funny Green Plant forums are the best place to get all the quality information you could want about growing with lights / which lights / etc. Nothing like a high-value crop to focus the mind - well, in the case of some of those growers, "focus the mind ... some of the time"!!