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#1 lespaulde

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Posted 27 March 2019 - 10:10 AM

Dear fellow pepperheads,

 

I've asked this in my glog too, but I figured this was a more general interest discussion, hence why I thought to open a separate topic... 

 

As some of us are not so lucky to live in a climate with year-round capability to grow pepper plants outside, or even having summers hot enough for growing superhots out in the open, I have just ordered a glass greenhouse (6.5 x 8.5ft / 193cm x 257cm) as I live in Northern Europe, Denmark to be exact. To maximise the impact I'm hoping this will have on my grow, I am now exploring possible ways of making sure to keep temperatures as high as possible during the night, especially in the colder ends of the season (spring and autumn, where night time temps are high 30s / low 40s (F) or 3-5 degrees C, with the occasional light frost at night.

 

I really appreciate the great suggestions I've already seen in the forums here, with keeping water containers (ideally painted black) in the greenhouse, so that they can absorb the solar heat and slowly release this during the night. I've also seen the bubble wrap suggestions along the walls which I'm also willing to give a shot, so currently my main concern is with the floor, and thus, the foundation. 

 

Initially, I was simply considering laying down ~4" / 10cm styrofoam plates at the bottom to insulate from the earth beneath, but my explorations online have introduced me to the concept of a "Swedish skirt" (no, nothing like what you'd initially imagine  :rofl: ). People are arguing that this is the proper way to insulate, by actually insulating the earth in the footprint of the greenhouse from the surrounding earth, so you can avoid it freezing and thereby letting it act as a heat reservoir. This is of course a lot more work in terms of labour upfront, and am just curious whether people in the less modest climates here have some experience to chime in with?

 

The principle looks as follows:

 

swedish_skirt.png

 
The insulation can also be put vertically, and should go down 60cm/24" to approx. frost-free depth. As it is a lot of manual digging though, I would love to hear if anyone has some concrete experience with how much of a difference this has on the night time temperature in the greenhouse during spring and autumn? To me it makes sense that if you can use all that dirt underneath the greenhouse as a heat reservoir, it should in principle have a really good effect. But if water reservoirs inside the greenhouse, combined with horizontal styrofoam plates on the floor can achieve the same effect, than I would probably rather go with that.
 
I wouldn't say I'm looking for a year-round grow (forget about that without active heating), but if I could extend, say, to early April until late October/November (i.e. no serious extended frosts), I'd be a happy camper. 
 
Many thanks for reading and any input you may have  :party:


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#2 CaneDog

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Posted 27 March 2019 - 11:32 AM

Wish I could offer some practical experience, but I haven't worked with anything similar before and could only speculate.  Congrats on the new greenhouse, though LPDE!

 

What a cool new thing.  I'm sure it will be great having it and help immensely with extending your season.


Edited by CaneDog, 27 March 2019 - 11:33 AM.


#3 lespaulde

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Posted 28 March 2019 - 01:01 AM

Thanks CD, and speculations are for sure welcome too, the discussion is worth having imho LOL...

I'm indeed excited to see how the plants will do, and if I get to move and keep them out for a bit longer too, this would certainly be a big bonus.

Ideally, I'd like to keep night time temps >50F/10C during the colder months, but not sure it will be possible without some sort of heat.

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#4 CaneDog

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Posted 28 March 2019 - 02:15 AM

So, what I wonder is will things get warm enough under the skirt to help keep the temps in the 50F/10C range you're aiming for or would it be better to simply insulate against the dirt - is it more of a freezing protection thing or does it really give off some warmth?

 

I do like the idea of using water containers as a heat sink and I do know those will get plenty warm from sunlight, especially if painted black.  I've seen people use the 55 gallon black drums as the supports for the tables to get a lot of mass in and directly under the plants. 

 

There's also thermal blankets.  Do you plan to use anything like that?

 

Hey, at least this is a bump!   Maybe someone who actually knows what they're talking about will see it and chime in.



#5 floricole

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Posted 28 March 2019 - 07:08 AM

water is the best for medium for retaining the heat, almost twice as stone.

 

here is what I will do for my greenhouses.

https://www.mcgill.c...atingreport.pdf

 

 



#6 Nulle

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Posted 28 March 2019 - 11:11 AM

How about putting the bottom part of the greenhouse under ground along with the other things you came up with? 30-40 cm?



#7 m1hagen

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Posted 28 March 2019 - 03:28 PM

water is the best for medium for retaining the heat, almost twice as stone.

 

here is what I will do for my greenhouses.

https://www.mcgill.c...atingreport.pdf

 

 

That was an interesting read.  Thanks!



#8 lespaulde

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Posted 29 March 2019 - 05:44 AM

So, what I wonder is will things get warm enough under the skirt to help keep the temps in the 50F/10C range you're aiming for or would it be better to simply insulate against the dirt - is it more of a freezing protection thing or does it really give off some warmth?

 

I do like the idea of using water containers as a heat sink and I do know those will get plenty warm from sunlight, especially if painted black.  I've seen people use the 55 gallon black drums as the supports for the tables to get a lot of mass in and directly under the plants. 

 

There's also thermal blankets.  Do you plan to use anything like that?

 

Hey, at least this is a bump!   Maybe someone who actually knows what they're talking about will see it and chime in.

 

I agree that it's likely totally unrealistic to expect things to remain in the 50F/10C range at near freezing temps, without adding any extra heat; especially in the case of a few overcast days, things would probably quickly go south. And indeed, my question is also mainly related to, will it add a few degrees to the greenhouse temperature, or will it merely protect against frost (if even that?). I guess this is totally location dependent and hence why the question is not answerable up front. I hope to see what people's experiences are, and am finding a few places in other forums where people are commenting a little bit in this direction. But all seem to suggest that to really ensure frost-free, you need active heat input, which of course could be done via a sun-based method as suggested by floricole below.

 

And yes, the water containers will for sure be my starting point, together with the swedish skirt idea, and see which improvements will be needed over the years to come. This is not a one season project anyway, so I think it will be fun to explore some options over the next several years.

 

Thermal blankets would for sure be beneficial, but since the require daily putting on/ putting off, I'm not convinced this fits perfectly with my lifestyle... ;) But covering the glass with big-sized bubble wrap might be sufficient to keep an extra degree or 2 inside overnight, and should still let sufficient light through for growth and warmth during the day.

 

Haha and defo, a bump is always nice, but your input has also already been extremely valuable, thanks a lot! :)

 

water is the best for medium for retaining the heat, almost twice as stone.

 

here is what I will do for my greenhouses.

https://www.mcgill.c...atingreport.pdf

 

 

 

 

Very nice article, thanks Floricole! I have also seen similar ideas implemented in other places, and would be keen on trialing some of this in a year or 2 myself. I love a bit of DIY, especially involving electronics, although I won't have electricity down where the greenhouse is, so will need to tinker with solar. I've even seen solutions using, e.g., 2x 200W solar panels combined with a water heating element, which heats water in barrels buried into the ground. This definitely seems like something worth trying too, but it also should remain a cost-efficient solution so will need to do much more investigation before committing. 

 

How about putting the bottom part of the greenhouse under ground along with the other things you came up with? 30-40 cm?

 

Thanks Nulle, I can see you have experience growing in these parts, as I've now also seen this being suggested in other forums after I started looking based on your post, that should definitely help too! Only problem for me is getting rid of that much dirt is practically unfeasible, given how our garden is laid out and I'd have to get it all out one wheel-barrow at a time. But certainly worth keeping in mind, thanks! :)






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