Winter temperatures in Alliance, Nebraska can drop to -20°F (the record low is -40°F/C), but retired mailman Russ Finch grows oranges in his backyard greenhouse without paying for heat. Instead, he draws on the earth’s stable temperature (around 52 degrees in his region) to grow warm weather produce- citrus, figs, pomegranates – in the snow.
Finch first discovered geothermal heating in 1979 when he and his wife built it into their 4400-square-foot dream home to cut energy costs. Eighteen years later they decided to add a 16’x80′ greenhouse in the backyard. The greenhouse resembles a pit greenhouse (walipini) in that the floor is dug down 4 feet below the surface and the roof is slanted to catch the southern sun.
To avoid using heaters for the cold Nebraska winter nights, Finch relies on the warm underground air fed into the greenhouse via plastic tubing under the yard and one fan.
Russ Finch: Thank you Kirsten for the great video it raised so many questions I thought I needed to answer some.
Pollination: There area lot of misconnects about pollination while most plants can benefit not many require pollination to produce. While citrus might benefit they set so much fruit that they abort until they can support what remains. The only plant we need to hand pollinate is the pomegranate.
Bees: If there are bees in the area they will find their way into the unit through the open ventilation windows.
Co2: Is overblown there seems to be no shortage in our system we have trouble keeping growth under control.
Latitude: We have learned so much about latitude with this project mostly it isn’t reliable for gaging heat and cold. The important thing is local climates. South of Oslo Norway is around 57° latitude where we are 42° but their winter average is 10° warmer than ours. The ocean and lake effects influence also. 52°: Lots of confusion about the temperature of the earth in relation to the greenhouse temp. The blower for the earth geo only turns on at 50° or below until then the warmth from the pit radiates heat and during the day in the middle of a February day, outside temp. 20° if the sun is out the temp at 6′ will be around 80° and the peak of the unit will get to over 124°.
Radon: WE have never heard of radon problems probably because the solution for radon is ventilation and that is our whole system.
Break even point; We have 41 units all over the U.S. and Canada now and the oldest units growing commercially are less than 3 years old so we have little information.
The typical 96′ greenhouse for local growing will cost about $24,000 if you have access to a backhoe and can do the labor. That size unit can support around 18 citrus trees that will take up 20% of the growing area. The citrus will produce fruit from the first year and be what we would call mature ( about 100# per tree) in from 6 to 12 years. The rest of the growing area can be used for any crop and should produce income to pay for the unit before the citrus is mature.
Grants: We have shied away from outside money after being approved for a $70,000 grant from the University of Nebraska only to have them decide to “not release the funds” after we had started to build. At that time we scaled back on the size and financed it our self.
Insects; Very little problem with insects after the first 3 years when we stopped using toxic chemicals and started using Horticulture oil (ultra refined mineral oil) it is safe and effective we just tree the problem area not the entire unit.
Agriculture needs to grow this way; This type growing can produce some of our table vegetables and fruit but there is no way we can produce enough to replace conventional farming.
We have skeptics that say this won’t work when I’m told that I pick an orange and try to figure where I went wrong while I eat it.
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