Setting up my solar greenhouse.

[stevelau1911]

One thing I've always wondered about is if I install a 400 watt led setup or something along that lines inside of my greenhouse, will it result in significantly more growth in the following year. The one problem that goes along with that is that daytime temperatures inside the greenhouse will typically only be in the 30s-60s during the daytime which is nowhere close to where they need to be for optimal photosynthesis, and due to excellent insulation, even if a lot of photosynthesis occurs, the carbon dioxide levels will likely become the limiting factor so I've resorted to not heating or lighting the greenhouse at all.

How have those LED lights done so far?
I did try a 90 watt UFO light in the past many years ago with unsatisfactory results, but what you have is likely much stronger and more advanced than the cheap light I had.

Here's a greenhouse with the same frame as the one I have now, but around $53 cheaper. I would have purchased this one if it was available 3 months ago.
http://www.ebay.com/itm/Green-Garden-Ho ... 2a344efb03

[terrabamboo]

I just checked a some fargesia I had thought looked DOA but maybe the LEDs helped it pull through? nothing to compare to though.



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[stevelau1911]

I've tried to get fargesia growing indoors a few times already and they usually do lose most of their leaves upon going indoors, but will often stay alive until the spring. Once spring comes, they seem to have trouble adjusting to the outdoor conditions, and may stay alive for a while, but it seems like they don't have the energy to produce any new growth, and eventually die off.

It may be due to the lack of vernalin or the plants just get aren't hardened off enough to go outdoors. I think in your area, fargesias would be fine staying in pots outdoors all through the winter because they seem to be even a bit hardier than most phyllostachys.

[terrabamboo]

Steve,

Did you ever look at this article? http://www.permaculture.co.uk/articles/ ... greenhouse
He describes running tunnels under the soil as a collector of heat. I think.

[stevelau1911]

I have looked into that method before however the bicolor inside my greenhouse with its rhizomes roaming around would make it unfeasible until I create another greenhouse which will be strictly used for potted plants.

One possibility is to build a nice deep well inside of a large greenhouse, then put a lid on it with a fan which can vent warm air into the rest of the greenhouse. Water can also be pumped out of that well to irrigate the plants inside and this would make water barrels obsolete. The soil temperatures more than 25 feet in depth should also be greater than 45F year round even this far north.

I believe that in order to make it worth the effort, I would need a greenhouse that exceeds 1000 square feet of floor space. The benefit in this is that it would only take around 15 watts to run a small fan to get the same amount of heat that you would in using a 1500 watt heater by using the natural heat of the earth.

[MadHatter]

I wish I could get away with heating my greenhouses this way. Nice work! Looks like you will be able to accomplish your goal.
There are plans for a solar heater on the web using a series of soda cans in tandem which are painted black but this requires a small fan to circulate the air through the cans which extract solar heat. Wouldn't do you any good at night but would certainly help during the day when it gets frigid out.

[stevelau1911]

The one issue with relying on solar heat is that with only 8 hours of potential daylight, and 85% of that time likely being cloudy which is typical for winters in great lakes, you will only get about an hour of the heating effect on average per day through the winter. That's just not very efficient especially since the already weakened daylight gets filtered through the clouds which makes it have very little solar value. It is true that you can go 2 whole months without a sunny day during the winter in this region.

It is currently 17.2F outdoors, but 25.3F inside the greenhouse, and we haven't had sun for 5 days so far so the heat trapping ability of the 9 (55 gallon barrels) along with tight insulation is still making a huge temperature differential. The only real threat is if it gets close to 0F which will drip the greenhouse temperature down below the mid teens which is just about the point where the potted bamboos inside the greenhouse may be at risk of freezing. That is the only situation where I would waste my heating oil, and it should take roughly 1/8 gallon of oil to raise the temperature inside the greenhouse about 5F for one night.

If we get a record setting low where it gets way below 0F, that's when I will be forced to break out my 100 watt space heater. Bamboos are fairly hardy so heating is not very hard in my case.

[MadHatter]

There is another option which is making a large compost heap right outside your greenhouse and coiling black plastic water line in the center and then looping in through your greenhouse. Horse manure mixed with leaves and some water can create 130 degree plus temps. It would need to be a pile of at least 3-4' tall to achieve those temps. It could be placed inside of the greenhouse as well but at a loss of usable space and added difficulty in turning it, but would eliminate the water line and pump to circulate water through the line. There is also the option of digging trenches within the greenhouse and laying green horse manure in them at least a foot deep and cover with a few inches of sand or soil. This would generate heat as well. A lot of sweet potato farmers use that method to produce slips in the winter in a simple cold frame which require about 80-F to sprout. Horse manure is the best at producing heat but just about any green manure would work.

[terrabamboo]

I have about 200 cans out of my 270 can requirement for the soda solar heater I plan on enhancing the design I found online a bit by adding R30 insulation and a small solar-powered dc computer fan to push air.

[stevelau1911]

I'm guessing down south, sunny days during the winter must be normal eh. Solar heating does require sunny days to be effective. I think the insulation and heat sinks will be necessary to hold in that heat that is harvested through the long nights of winter.

Anyways to update on the status on the greenhouse, it is currently 17.6F outdoors, and 25.5F in the greenhouse, and the water barrels don't show any signs of getting frozen despite temperatures being consistently below freezing.

It seems like a 5-10F temperature differential seems to be the norm with this greenhouse which should mean that the bamboos inside are very safe. When it dipped to 7F, the greenhouse got down to 22.4F. As long as the barrels of water do not freeze over, it doesn't look like there will be any issues.

One thing I do need to rely on is to get at least some sunny days through the extreme cold spells because full sun is usually enough to drive the greenhouse temperatures 30F or more over the outdoor temperatures, especially with the reflection of the snow. We should get some sunshine on the 19th which should allow the barrels to heat back up a little bit in preparation for the extremes.

[stevelau1911]

During the cold week of temperatures below freezing, mostly 24F-12F, and hardly any sun, it looks like the 9 greenhouse water barrels still couldn't freeze over entirely. Once it melted a bit during the thaw recently, I only saw about 1-2 inches of ice on the surface of them which is pretty amazing. They have become completely unfrozen now, but even with a winter of below average temperatures, it looks like the average greenhouse temperature has a hard time getting below freezing.

Next week is supposed to be extremely cold again, maybe the coldest week for the winter, but with daylight hours rebounding after that, I really doubt that these water barrels can freeze over that easily. In my climate, the average winter temperature should bottom out at 24-25F, but I doubt that it gets below that in the greenhouse that often over the span of an entire week.

Here are the water barrels during the thaw while ice was still in the barrels. This actually lowered the greenhouse temperature below the outdoors temperature by as much as 10F while the barrels were warming back up cooling the rest of the greenhouse.

[stevelau1911]

I do realize that my barrels of water inside the greenhouse may freeze more than just a little bit this time around with 2 nights of forecasted sub-zero temperatures so I went ahead and tested my 100 watt ceramic space heater.

It started out at 20.2F outdoor/30.3F greenhouse, and after 1 hour of heating, the temperatures were 21.4F outdoor/37F greenhouse. It does take some time to heat up the whole greenhouse, but 5-6F of heating at freezing should equate to 12-15F of heating if it gets down close to 10F inside the greenhouse which is many times more power than the kerosene lamp. There was also a sudden rise in the GH temperatures coinciding with turning on the heater which leveled off, and dropped as soon as the heater was turned off so the 15F+ differential would not have happened naturally. It was also placed towards the middle of the greenhouse away from the temperature sensor. The only time I see it necessary to use this is if the barrels do freeze over all the way, and there's the chance of temperatures lower than 15F which may happen in the next couple nights, but based on the forecast, this may be the last time I may need to use it.

Based on the results I saw, a 100 watt heater is more than enough in terms of usage as a frost heater in zone 6 for temperate bamboos in a 20X12X8ft greenhouse.



This thing is literally the size of a baseball. Here's the link to what I'm using.
http://www.aliexpress.com/item/Mini-Por ... 24681.html

[Alan_L]

Steve: I wonder if a birdbath heater in one of the water barrels would be just as effective? Seems like it would be safer too, since if the power goes out you still have the thermal mass of the water.

[stevelau1911]

I've thought about it, but don't really know how well it can work since it would take a while before the heating effect takes place. That means that it would have to be turned on well before the freeze.

If my current heater stopped working for some reason, I would just have to resort to using the oil lamps which won't create as big a temperature differential, but should be enough to make a difference in stopping temperatures from getting too cold.

This looks like a pretty good one. I just don't know how good these electronics do in the water in the long term due to the freeze thaw cycle.
http://www.ebay.com/itm/ALLIED-BIRD-BAT ... 564728d230

[Tarzanus]

I have 400W aquarium heater that can be set to maintain temps from 15 to over 30C. A couple of those could turn your greenhouse into a foggy sauna.