All year greenhouse

[Acuario]

I have been given an evacuated tube solar water heating system and am thinking of how to incorporate it into a climitized greenhouse system.

I'm planning to buy a 13M2 greenhouse so would like to try to get the whole thing built at the same time.

My idea is to use the solar water heater to collect heat during the day and to have it connected to an underfloor heaing system in the greenhouse to maintain the soil temperature overnight and during the morning. The heating panels would be covered with soil in raised beds.

I'm also thinking of using a temperature/humidity sensor coupled to a processor based control system and (if I can work out how to construct them) motorised roof windows. The controller will control the heating/watering/windows to maintain an optimum growing condition.

Has anyone done anything similar to this? Any pointers/suggestions; soil depth/optimum temperature/humidity?

Nigel

[Daox]

Sounds like it will should work depending how much solar collector area you have and your local climate. At the very least it will increase the growing season.

I'd also suggest at least insulating around the perimeter of the green house, and if you can insulate the bottom of it and then dump soil into the insulated box you've made.

[Geo NR Gee]

It would be intersting to know how much of a storage tank you would require in order to heat the greenhouse in the coldest winter days.

My friend has a large greenhouse business and grows only part of the year. He said that he needs to always maintain about 70F in order for his plants to grow healthy. He grows strawberries, squash, tomatoes and some other vegtables. He said his major expense is heating.

After I explained about the ground source heat, his interest became apparent and wants to know more. But the idea of using evacuated tube solar heating and storage tanks may be less expensive?

Geo

[Daox]

Our neighbors have two greenhouses that are of fair size (not gigantic) on their 2 acre lot. They're made of two layers of plastic and they blow air between them creating a baloon effect and an air barrier for some insulation value. With this setup and some foam insulation around the perimeter they're able to grow year round. In winter they grow lettuce and spinach which can handle mildly freezing temperatures down to the high teens (degrees F).

[basjoos]

Spinach is cold hardy to around 0F. The cold hardiness of lettuce varies greatly depending on the cultivar, but the cold hardier lettuce cultivars can take down to 5F.

[remint]

Originally Posted by Daox

I'd also suggest at least insulating around the perimeter of the green house, and if you can insulate the bottom of it and then dump soil into the insulated box you've made.

I've even heard that adding digesting compost in this type of box surrounding the base, would additionally boost internal heat of the greenhouse.

[strider3700]

getting greens to survive the winter isn't overly difficult. Getting them to grow through the winter can be hard. They need to warm up during the day to grow. A greenhouse can help with this.

For kicks last winter I planted lettuce, carrots and beats in a front garden where I knew they would be sheltered from the worst of the weather and should survive. The did survive but didn't grow a bit from mid october until late march. I think with a small poly tunnel they'd have kept growing at least another month probably right through.

[remint]

Originally Posted by Daox

Our neighbors have two greenhouses that are of fair size (not gigantic) on their 2 acre lot. They're made of two layers of plastic and they blow air between them creating a baloon effect and an air barrier for some insulation value. With this setup and some foam insulation around the perimeter they're able to grow year round. In winter they grow lettuce and spinach which can handle mildly freezing temperatures down to the high teens (degrees F).

Low Cost DIY greenhouse design of similar construction:

greenhouse

[Indyplumber]

I was thinking of the same thing myself. I was going to DIY the collector and use an old 75 gallon water heater for storage and lay PEX under a 2' raised bed garden. Collector would be drain-back. I didn't think about insulating the sides of the bed though - good idea. Does the composting need a minimum temp to start breaking down? Anyway you might be able to get some 12v pumps to circulate though the collector and the radiant tubing and use a panel to charge the battery. You could EVEN get an 80 gallon electric water heater and just wire in the bottom element as a backup.

[basjoos]

Originally Posted by strider3700

getting greens to survive the winter isn't overly difficult. Getting them to grow through the winter can be hard. They need to warm up during the day to grow. A greenhouse can help with this.

For kicks last winter I planted lettuce, carrots and beats in a front garden where I knew they would be sheltered from the worst of the weather and should survive. The did survive but didn't grow a bit from mid october until late march. I think with a small poly tunnel they'd have kept growing at least another month probably right through.

Besides low temps, the other main factor causing limited plant growth in the winter is the short day length. This is why a lot of overwintered veggies that just sit there through Dec and Jan, then start growing from Feb on, despite Feb temps that are just as low as Jan temps. The higher your latitude, the more this is a factor in your plant's growth. At my latitude (34 N), most veggies remain in the doldrums from late Nov through most of Jan, even under cover. The main exceptions to this being lettuce cultivars developed in Europe for winter cropping and many overwintered Chinese crops. Compared with European spinach cultivars, Chinese spinach cultivars are less cold hardy but will keep growing and producing through the shortest winter days where European spinach just sits there. But as the days start to lengthen in Jan-Feb, the Chinese spinach will bolt while the Europeans will start growing nicely before bolting in Apr.