Bodged Greenhouse

[joz]

I've got a 18"x36"x54" plastic shelving unit from Home Depot. It's got "perforated" (grid) shelves, so I can hang my lights off them.

I'm thinking of getting a couple yards of 20ga double-polished clear vinyl, and cutting/folding/duct-taping it together to form a cover for the shelves, to make a wee greenhouse. I'll install a zipper down each side of the front, so's I can roll up the front panel, and some heavy-duty velcro around the perimeter at the bottom to keep the "walls" stuck down.....

Maybe install some smaller zippers for watering access, so's I don't have to open the whole thing and let the heat out. Hmmm.

I figure I'd use christmas lights for bottom/overall heat. It rarely (3x/year, and then only for a couple hours max) drops below freezing here. If I flip the shelving unit upside down, there are recessed bits that I could set the lights in for more direct contact with my flats. Dunno if it matters, or if I like this idea, or if there's a better way to do it.....

If I'm using what amounts to (very heavy) plastic sheeting, should I maybe do a double-wall?

If it's sitting on my rear porch (wood deck), do I need to cover/wrap the bottom (perforated shelving) as well?

What's the minimum amount of compost I could process inside to generate some heat? If I don't use the bottom shelf, I'd have ~36"x18"x18" available.

Any thoughts, critiques, or advice re my harebrained scheme would be most welcome.

 

[digitS']

I don't believe that it is a harebrained idea, Joz, if . . . these little shelters work. I guess they do because one can buy something like what you are thinking of from a number of sources. Another "if" is if you can keep track of the temperatures in something that small. You'd need to be around a lot because there isn't much room inside and heat will build quickly.

You live in a very different climate from my own and maybe you aren't going to be very far from that rear porch during the critical times that the shelter will need attention.

Here's a thought or 2, tho'. I don't believe you'd need to put 2 layers of plastic over it if there won't be room for dead-air space between them. Warmth will migrate easily thru the layers if there isn't insulating air.

Composting requires a minimum of 4' by 4' by 4', the people who know keep telling us. I doubt if you can get adequate decomposition to provide heat in anything smaller. Maybe heat storage in the form of water would work. It could even be moved indoors to warm and then back out at night.

About all I can think of.

Steve

 

[joz]

Well, I got the vinyl from JoAnn Fabrics during lunch today. 3.5 yards should cover the shelf unit, and the $7.99/yard was cheaper than I'd seen it elsewhere. Got up to the register and asked if there were any circular specials this week for which I was eligible, and the guy gave me 50% off! WOO HOO!

So far my total cost for this setup is $44... but I still have to buy fluorescent fixtures.

I'd planned on, if a double wall was required, figuring out a way to do an airspace.

I've considered doing black water in jugs as a solar "powered" thermal sink. Am intrigued by compost heat, but figured it was too small.

At 40*F typical daytime winter temps, I wonder how warm this will get in 5 hours of sunlight without any additional heat source? I think the biggest problem will be that our temps fluctuate pretty wildly all winter. Just two days ago it was 80*F, now it's 50*. This may be the "harebrained" part of the plan, thinking this is a good idea at all. I'd've maybe done better with a trunk, lights, and a heater.

Guess I've got to get a thermometer also.

I don't suppose y'all know of a small thermostatically controlled vent that would work for this kind of setup...?

 

[digitS']

The thermometer-controlled vent for my greenhouse is . . . me.

Thermometer sits here beside the monitor with the sensor in the greenhouse. I'm at a south window, also. Despite the sunshine, I'm nearly frozen in this position for weeks on end .

Lesa may have installed a thermostatically controlled vent that would work well enuf for a small set-up.

Steve

 

[dickiebird]

Here's a link to a you tube video that may be of interest to you.

http://www.youtube.com/user/webcajun#p/search/12/cjVP6nAZbi0

THANX RICH

 

[joz]

The thermometer-controlled vent for my greenhouse is . . . me.

Thermometer sits here beside the monitor with the sensor in the greenhouse. I'm at a south window, also. Despite the sunshine, I'm nearly frozen in this position for weeks on end.

Steve

Hey Steve... what thermometer do you use? I have a friend with a bbq/meat thermometer that sounds an alarm inside at a given temp on the grill outside, and I liked that idea but wasn't certain if I could find a similar item (or if a meat thermometer would work in a greenhouse).

After searching a bit I seem to have found thermometers with alarms, but the sales listings lack descriptions, and thus I am not certain that they are what I think they are. I do not need a thermometer with an alarm clock (?!), several of which I have seen in my searches.

The issue I will have is that I work full time, so I won't be able to adjust things during the peak sunlight timeframe. I'll have to set up the thing and monitor an empty environment to modulate the temps prior to installing the plants. Although I'm guessing that daytime temps will be sufficient without the thing being zipped up tight, so I can probly leave it open during the day and just heat it at night, which will be significantly simpler to control, no?

 

[lesa]

Yes, you have hit on the thing I discovered having my greenhouse. It is way easier to keep it warm, then to cool it off. Plants can take an amazing amount of cold- and will just plain burn up, if they are too hot. I think in your zone, you should be fine leaving it unzipped during the day, and just bundling it up in the evening. Throwing a blanket over the top of the whole set up will keep extra heat in too. The venting system I used on the windows of my greenhouse is really cool. It has wax inside the hinged arm- the heat softens the wax, and the windows open- the cool air hardens the wax and they close. Not sure how you could use this with plastic though...Keep us posted on your progress!