Tropical Fruit Forum - International Tropical Fruit Growers

Citrus => Cold Hardy Citrus => Topic started by: will2358 on October 19, 2019, 08:08:21 PM

Title: Frost Protection
Post by: will2358 on October 19, 2019, 08:08:21 PM
Well it's getting a chilly outside so I wanted to ask opinions on frost protection. So far I only have 4 that will remain outside this year. 3 in the ground and one in a pot. I was looking at Agfabric but does it really help on those really cold days. I was also looking at a MIgardener video and he wraps his trees in bubble wrap and a garbage bag. A few years ago I used a light and a PVC small greenhouse to protect a meyers lemon. I saw this on pinterest. I might build my pvc covers like this.
(https://i.postimg.cc/crP60GYh/pvc.jpg) (https://postimg.cc/crP60GYh)
Title: Re: Frost Protection
Post by: Bomand on October 19, 2019, 08:24:11 PM
I am in a little different zone than you. If we get a just bearly freeze I throw an old blanket over what I protect. If we get into the low twenties I use the blanket then wrap the whole thing in cheap blue tarp. Your protection will work for you...it looks like a mini greenhouse....lights in the canopy will also work.
Title: Re: Frost Protection
Post by: SeaWalnut on October 19, 2019, 08:32:20 PM
Keep in mind that air is the insulator( best insulator in the world) so a double layer give you insulation while a single layer has no insulation propertyes but will get warm if the sun shines because of the greengouse effect.
That heat from the greenhouse effect can radiate a few hours after the sun is off.
Bubble wrap or any type of transparent plastic wrap with an air gap sealed in between is a good insulation and you also get the greenhouse heating  effect during the day.
Think of stirofoam insulation.Its the air trapped in the stirofoam that insulates ,not the plastic itself.
Title: Re: Frost Protection
Post by: will2358 on October 19, 2019, 08:42:01 PM
Keep in mind that air is the insulator( best insulator in the world) so a double layer give you insulation while a single layer has no insulation propertyes but will get warm if the sun shines because of the greengouse effect.
That heat from the greenhouse effect can radiate a few hours after the sun is off.
Bubble wrap or any type of transparent plastic wrap with an air gap sealed in between is a good insulation and you also get the greenhouse heating  effect during the day.
Think of stirofoam insulation.Its the air trapped in the stirofoam that insulates ,not the plastic itself.

The styrofoam sounds like a good idea. We can get snow and ice during a winter.
This is a little off topic but what is up with all of the RogerShula quest post in citrus about nothing that has to do with plants.
Title: Re: Frost Protection
Post by: Bomand on October 19, 2019, 09:00:30 PM
Someone is spamming the forum.
Title: Re: Frost Protection
Post by: Millet on October 20, 2019, 12:57:02 AM
Sorry for all the spam on this site.  I had to go through the process of deleting each spam post one post at a time.  I have asked the administration how to faster handle this situation.
Title: Re: Frost Protection
Post by: Bomand on October 20, 2019, 10:20:52 AM
Good job Millet. I really do not understand spammers.....I have no desire to bomb someones site....old school I guess....I just dont go where I am not wanted.
Title: Re: Frost Protection
Post by: will2358 on October 20, 2019, 12:11:35 PM
Thanks Millet for deleting it. Do you have any recommendation on the frost the frost protection?  I really want my trees to make thru the winter. Next year I have lots more to plant out. Most of my trees are only a foot or so tall and I was advised not to plant them this year. I also have seedlings grown from seed that I will plant some out next year. I might try the Plant Protector for the seedlings next year. https://www.growitnow.com/product-category/plant-protectors/ (https://www.growitnow.com/product-category/plant-protectors/) 
Title: Re: Frost Protection
Post by: Bomand on October 20, 2019, 01:05:13 PM
The water filled plant protectors will probably work like a charm. The only drawback is the small size. You stated your plants are small and these would fit. I have a similar working home made device that works. I take a five gallon plastic bucket (availiable at all the big box stores), cut the bottom out of it and make a cut from top to bottom on the side. This allows you to flex the bucket enough to get it around your plant. Put the bucket around the plant, fill with sand enough to cover the graft union for grafted plants. Throw something over the top and you are ready for a cold night. The bucket can be left on for the duration of the deleterious cold weather. Just take your cover off the top during good days. If you leave it on for extended times be sure your trunk does not sun scald when you take it off. You can paint trunks with water based latex paint that is left over from the last time you painted.
Title: Re: Frost Protection
Post by: will2358 on October 20, 2019, 04:09:58 PM
Thanks Bomand! I have lots of 5 gallon buckets from my hydroponics days. I will use the buckets if they are not too large next fall.
Title: Re: Frost Protection
Post by: Citradia on October 20, 2019, 08:04:45 PM
If you have snow and ice make sure your structure can hold up under the weight of it. My bent over pvc pipe domes secured to ground with rebar stakes hold up under heavy snow but as tree gets about 6 ft tall, I end up having to build wooden structures around each tree.
(https://i.postimg.cc/YhYzKxG4/0-F18926-D-0-B9-D-4331-BA7-D-5-B94-EBC18-CE6.jpg) (https://postimg.cc/YhYzKxG4)

(https://i.postimg.cc/jwfrQ92q/3-A70-EAB9-4-D6-C-436-B-9-B15-D3-C2-A4-FA7-D38.jpg) (https://postimg.cc/jwfrQ92q)

(https://i.postimg.cc/ThycQxTJ/6673-AE99-00-B3-4-F11-A9-F0-3-CE201214-A5-F.jpg) (https://postimg.cc/ThycQxTJ)

(https://i.postimg.cc/7JTML3KW/7044761-B-3-CDB-4682-9-F62-359-B7-F0-B7-D30.jpg) (https://postimg.cc/7JTML3KW)

(https://i.postimg.cc/bD4k4GqH/BFE34-D5-B-29-B1-498-D-A98-D-1-A217-DB1099-E.jpg) (https://postimg.cc/bD4k4GqH)
Title: Re: Frost Protection
Post by: brian on October 21, 2019, 09:25:54 PM
Ive read wrapping christmas lights (non-LED) around the tree and turning them on when it freezes can keep the tree warm enough.  Ive never tried it personally
Title: Re: Frost Protection
Post by: will2358 on October 21, 2019, 09:47:26 PM
If you have snow and ice make sure your structure can hold up under the weight of it. My bent over pvc pipe domes secured to ground with rebar stakes hold up under heavy snow but as tree gets about 6 ft tall, I end up having to build wooden structures around each tree.


Do you have hot water in the trash cans?
Title: Re: Frost Protection
Post by: Citradia on October 21, 2019, 09:50:36 PM
I cant find old-fashioned Christmas lights and my POA wont let us do Christmas lights for half the year anyway. Ive wondered about propane patio heaters but I dont think it would be economical nor would the heater last more than a few hours.
Title: Re: Frost Protection
Post by: Citradia on October 21, 2019, 09:57:46 PM
The trash cans are filled with well water or rainwater in late October and dumped out in spring in early May. The sun is supposed to heat the water in black cans during day and the water in the cans provides heat to the enclosure during freezing temperatures. As water freezes it gives off some heat. The volume of water in enclosure also means less air space for my electric space heaters to heat when the thermo cubes turn them on when temperature gets to 35 degrees.
Title: Re: Frost Protection
Post by: Citradia on October 21, 2019, 10:10:41 PM
Heres pics of the wooden frames that I put up around my owari and meiwa this weekend. The trees are now too tall for my 17 ft long pvc pipe domes. They are screwed together so Ill take them down in spring. Ill have to put the 4 mil plastic on the frames next weekend. Usually get first freeze at Halloween or at least by twelfth of November. My Croxton is still small enough for pvc dome.
(https://i.postimg.cc/fSVRvdCs/24-ABE534-6765-4-BDA-9-F55-1481-E660848-C.jpg) (https://postimg.cc/fSVRvdCs)

(https://i.postimg.cc/6TFWXyz7/C00-C6-D63-5-E46-4482-9-E12-5521-EA343-ECE.jpg) (https://postimg.cc/6TFWXyz7)

(https://i.postimg.cc/MnSznNCq/FCEE84-FE-76-B2-4172-954-D-188-D1-CE8-D6-AE.jpg) (https://postimg.cc/MnSznNCq)
Title: Re: Frost Protection
Post by: brian on October 21, 2019, 11:09:07 PM
That looks really solid.  Nice
Title: Re: Frost Protection
Post by: usirius on October 22, 2019, 01:49:17 PM
Interesting winter protection solution from online nursery Ahrenz+Sieberz:

https://www.as-garten.de/ueberwinterungszelt-igloo (https://www.as-garten.de/ueberwinterungszelt-igloo)

(https://i.postimg.cc/hJvPkNZV/igloo-1-1000x1000.jpg) (https://postimg.cc/hJvPkNZV)

Of course, if you have some technical skills, you can reproduce this solution in these or other dimensions.
Title: Re: Frost Protection
Post by: Bomand on October 22, 2019, 03:01:54 PM
Interesting....a great idea for those that need extended protection. Cost would determine feasability of construction.
Title: Re: Frost Protection
Post by: lebmung on October 24, 2019, 05:59:57 AM
Think of stirofoam insulation.Its the air trapped in the stirofoam that insulates ,not the plastic itself.

Not necessary see high density XPS
Title: Re: Frost Protection
Post by: lebmung on October 24, 2019, 06:06:54 AM
Plastic closures are dangerous during the winter such are these domes especially in zones under 7.
The thing is that air get trapped inside with a high moisture content which make it a bad insulator. for citrus is not a good long term solution like 3 months long winter.
Why? Because the plants need aeration, citrus sleeps well with dry cold air, not humid. This will lead to disease and die back.
Title: Re: Frost Protection
Post by: usirius on October 24, 2019, 06:11:43 AM
You're right. When temperatures in the inner side gets above 0C there water will condense and that promotes mold and rot. The trick is to open the protection than and let new dry ait in. And also of course close when freezing temperatures will come again (after sun is going away or after taupe periods)  I do so since years and than this principle will work well.
Title: Re: Frost Protection
Post by: TooFarNorth on October 24, 2019, 07:03:08 AM
This is how I protect mine.  I am in zone 8a also, about 75 miles south of you.


(https://i.postimg.cc/dkWSZ1T3/1120181342b-HDR.jpg) (https://postimg.cc/dkWSZ1T3)

So far has worked fairly well.  I haven't lost a tree yet, though I have had some minor damage.


TFN
Title: Re: Frost Protection
Post by: TooFarNorth on October 24, 2019, 07:23:38 AM
That is frost cloth gathered at the bottom, ready to pull up and secure with ball bungee on cold nights.  I use 7 ft. 1 1/2 oz. on smaller trees and 12 ft 1 oz on taller trees.


(https://i.postimg.cc/rd0qyKZV/1120181342a-HDR.jpg) (https://postimg.cc/rd0qyKZV)

Keeping the ground clear and bear under the tree helps provide heat from earth heat sink.  If possible block north wind also. 


TFN
Title: Re: Frost Protection
Post by: Bomand on October 24, 2019, 07:42:31 AM
Any cold protection requires attention and maintenance. As was stated, in areas where condensation becomes a problem proper and timely opening and closing the containment is a must. The secret for cold protection is: Find out what works for you in your area and do the work required to facilitate good cold protection. Not every soloution works for everyone and expermentation is required to determine what wodks for you.
Title: Re: Frost Protection
Post by: Citradia on October 24, 2019, 08:59:36 PM
Thats right, Bomand. When its not freezing, I roll up the door side of my enclosures to ventilate my trees and put concrete blocks under the sides of plastic to lift it and vent underneath on all sides. I water my trees in the enclosures weekly and try to saturate soil before a freeze to help add freeze protection and hydrate tree. This was recommended at our southeastern citrus expos and I havent had a problem with rot in the past seven years. Frost cloth does not insulate enough against the severe cold I get here in western NC, so I use 4 mil plastic sheeting. Ive seen it not get above freezing for the whole month of January several years ago. Happy winterizing to one and all!
Title: Re: Frost Protection
Post by: will2358 on November 19, 2019, 06:12:01 PM
I cant find old-fashioned Christmas lights and my POA wont let us do Christmas lights for half the year anyway. Ive wondered about propane patio heaters but I dont think it would be economical nor would the heater last more than a few hours.
What about an halogen bulb shop light? That is what I plan on using, with an outside timer.
Title: Re: Frost Protection
Post by: brian on November 19, 2019, 06:30:47 PM
A full 15 or 20lb "grill tank" of propane should last 24hrs on the low setting.  I have used them extensively.  They make a lot of heat.

A halogen bulb is probably fine for keeping a small area a little warmer than outside
Title: Re: Frost Protection
Post by: Citradia on November 19, 2019, 07:40:25 PM
I tried shop lights under some young trees that Id surrounded with plastic over wire cages years ago. Tried reptile purple heat lamp bulbs. I found unfortunately that half the time I would find the bulbs shattered the next morning; I think the bulbs got condensation on them and froze and when they came on, heated up, and shattered. Im done with light bulb heat and just do space heaters with fans to circulate air.
Title: Re: Frost Protection
Post by: Ilya11 on November 20, 2019, 03:56:57 AM
Here we have heating cables for the water pipe protection.
They work well  to keep the temperature above freezing. I guess they are also available in USA.
Title: Re: Frost Protection
Post by: brian on November 20, 2019, 09:09:13 AM
I tried shop lights under some young trees that Id surrounded with plastic over wire cages years ago. Tried reptile purple heat lamp bulbs. I found unfortunately that half the time I would find the bulbs shattered the next morning; I think the bulbs got condensation on them and froze and when they came on, heated up, and shattered. Im done with light bulb heat and just do space heaters with fans to circulate air.

Ah I hadn't thought about the sudden temperature change breaking the bulbs.  Good point. 
Title: Re: Frost Protection
Post by: hardyvermont on November 20, 2019, 03:20:09 PM
A 250 watt space heater for $12 is enough to keep a tarp covered area 10 x 17 near or above freezing most winters.  Citrus go dormant in cold weather, I am still learning how long they can be kept covered without damage.  Last an Owari was kept mostly in the dark until April, and had a large crop of fruit this year.
Title: Re: Frost Protection
Post by: Millet on November 20, 2019, 05:51:18 PM
Back in the days of Kings, Queens and large castles, they put their citrus tree in their dark cellar throughout the winter months and they did fine.
Title: Re: Frost Protection
Post by: lebmung on November 20, 2019, 06:46:27 PM
6 to 7 weeks in dark at 6-8 C in a cellar they will survive, tested. More than that they start losing leaves.
Title: Re: Frost Protection
Post by: lebmung on November 20, 2019, 06:47:23 PM
Has anyone used Infrared bulbs? The one used to heat the chickens.
Title: Re: Frost Protection
Post by: will2358 on November 24, 2019, 06:44:11 PM
Has anyone used Infrared bulbs? The one used to heat the chickens.
The infared bulb sounds like a great idea. I will place my light on a timer.
(https://i.postimg.cc/pmCyZGpX/timer.jpg) (https://postimg.cc/pmCyZGpX)
Title: Re: Frost Protection
Post by: kumin on November 24, 2019, 06:58:15 PM
will2358, I believe my preference would be thermostatic control rather than time control, simply because temperature excesses would have the lamp turn off regardless of time of day, to avoid overheating damage. Likewise very cold temperatures during daytime would turn the lamp on regardless of time of day.
Title: Re: Frost Protection
Post by: will2358 on November 24, 2019, 08:42:40 PM
will2358, I believe my preference would be thermostatic control rather than time control, simply because temperature excesses would have the lamp turn off regardless of time of day, to avoid overheating damage. Likewise very cold temperatures during daytime would turn the lamp on regardless of time of day.
Lack of funds and the fact that it is a plastic cover for 1 plant instead of a greenhouse. I already have the timer and I only need to buy the bulb. Actually when I did have my greenhouse I used a small electric heater on a timer to keep things from freezing. I heated the GH like that for a few years.
Title: Re: Frost Protection
Post by: Citradia on November 24, 2019, 09:28:35 PM
You can get a thermo cube from Tractor Supply or a similar thermostatic device for under $15 at Lowes. Or online. I plug my heaters into a thermo cube at beginning of winter and let it protect the trees for me while knowing Im not wasting as much electricity or possibly over heating my trees and causing them to break dormancy. My only labor for the trees after winterizing them is watering at least once a week and opening and closing the door on enclosure to vent when not freezing temps, again to prevent overheating and breaking dormancy.
Title: Re: Frost Protection
Post by: will2358 on November 25, 2019, 03:22:41 PM
You can get a thermo cube from Tractor Supply or a similar thermostatic device for under $15 at Lowes. Or online. I plug my heaters into a thermo cube at beginning of winter and let it protect the trees for me while knowing Im not wasting as much electricity or possibly over heating my trees and causing them to break dormancy. My only labor for the trees after winterizing them is watering at least once a week and opening and closing the door on enclosure to vent when not freezing temps, again to prevent overheating and breaking dormancy.
Will the thermo cube work on a heat lamp?
Title: Re: Frost Protection
Post by: kumin on November 25, 2019, 03:30:01 PM
The Farm Innovators Thermo Cube is a temperature controlled electrical outlet adapter.
This is model TC-3 available at Tractor Supply, as long as the amperage is not exceeded it should be fine.
    It operates with any 15 amp 120 volt electric heater or fan. Less than 15 amp heating device will not be a problem.
    It plugs directly into any standard outlet.
    It is thermostatically controlled and turns the power on and off automatically, according to the outside ambient air temperature.
    It converts a single outlet into a convenient double receptacles.
    It saves money by using power only when temperature requires.

One requirement is that the Thermo Cube is at the same temperature exposure as the plants. Within the enclosure is probably best so it can monitor the plant"s environment.
Title: Re: Frost Protection
Post by: usirius on November 25, 2019, 04:30:07 PM
For 20 years I have been heating my approx. 15 m2 cold greenhouse frost-free with two small standard heating fans - two of them because experience has shown that one can fail at a time...so the greenhouse doesn't completely freeze in severe frosts.....the heating fans can be set to 1500 or 2000 watts. They have included also a thermostat, but it is too imprecise for me. Therefore I set it to full heat and control the fan heaters again separately with two room thermostats / socket thermostats with wired sensors, which I can position away from the fan heaters. So both fan heaters heat independently of each other in the greenhouse, and if one (or a thermostat) fails the other can still heat....that was already the case three times in the time and has ensured the plants in the meantime as long as the survival, until I could determine the Pro and solve. blem have determined... The thermostat setting is 2C (35.6F) as the lower limit and 4C (39.2F) as the upper limit to minimize heating costs and still ensure survival, so I winter not only more robust citrus but also more sensitive ones like the Australian citrus or warmth-loving potted plants like Natal plum (Carissa macrocarpa) or Surinam cherry / Pitanga / Kirschmyrte (Eugenia uniflora) or the Kingprotea (Protea cynaroides)too, survive this very well! Thermocontrolled heating also avoids overheating when for example sun is shining in a clear winter day into the green house. Of course when there are no freezing temperatures outside I am opening  the windows as long the sun is shining to avoid overheating by sun shine also.
Title: Re: Frost Protection
Post by: kumin on November 25, 2019, 05:41:46 PM
1500 Watts is likely serious overkill for a small enclosure. The wattage should not be higher than the equivalent wattage of a correctly sized lightbulb.
Title: Re: Frost Protection
Post by: usirius on November 26, 2019, 03:11:13 AM
Hi, as I have said the 1500 Watts in my case are controlled by a thermostat - therefore 1500 Watt are not overdimensioned. In case of strong freezes the 1500 Watt are not enough for heating up such a large greenhouse frost free.....to  make sure, I have pottet plants in this green huse, which are not able to withstand freezing temperatures below 32F (0C) ....
Title: Re: Frost Protection
Post by: kumin on November 26, 2019, 05:29:18 AM
In a very small enclosure as pictured, a very powerful heat source can overheat plants before the thermostat may react. This should not be a concern in an appropriately matched heater and enclosure. My concern was that the original poster may have an enclosure not much larger than the tree, in which case the tree could be vulnerable to scorching. In a larger enclosure this is much less of a concern.
Title: Re: Frost Protection
Post by: usirius on November 26, 2019, 11:26:42 AM
Yes Kumin you are right, in a small enclosure of course such an heater would overheat and make no sense. Of course the power should be adapted according to enclosure which should be heated. Thanks for the hint.
Title: Re: Frost Protection
Post by: will2358 on November 26, 2019, 01:17:22 PM
I referring to the infrared bulb mentioned by lebmung. Will it work on an infrared heat lamp?
Title: Re: Frost Protection
Post by: Citradia on November 26, 2019, 08:25:55 PM
All I know is the thermo cube is basically a switch plugged into a wall socket or an extension cord and when the temperature around it gets to 35 degrees, the switch allows electricity to flow to whatever device you have plugged into it. You could plug a lamp, a toaster, a hair dryer, a radio, a space heater, a shop light, I imagine an infrared heat lamp, anything you want. I plugged shop light with a purple reptile heat bulb into it and it worked but the bulb busted due to condensation on the glass bulb being cold and then the heat shattered the glass. Id just hope the infrared bulb, if glass, wont shatter in an outside humid environment.
Title: Re: Frost Protection
Post by: Citradia on November 26, 2019, 08:28:59 PM
https://media.tractorsupply.com/is/image/TractorSupplyCompany/2170275?$456$
Im trying to post a pic of thermocube I got off Tractor Supply site.
Title: Re: Frost Protection
Post by: usirius on November 27, 2019, 03:15:30 AM
According to my knowledge and experiences with infrared light bulbs I think they are warming the surfaces (leafes, stems, twigs) too hot. I would prefere normal light bulbs which I am doing for some plants I have in plein air with a simple frost protection, I do not use an thermo cube ecause I am using low wattages (between 3W and 20 W) I can let run them during frost periodes permanently - minimum for night - than switched by a timer - without any danger of damaging. From time to time I am looking at weather news for deciding to swithch bulb of,  or on or to change the bulb, use one  with more or less power.
Title: Re: Frost Protection
Post by: kumin on November 27, 2019, 04:09:56 AM
Usirius, I agree with your concern for overheating with heat lamps. I previously had a small duck hatchery and used heat lamps to brood newly hatched ducklings. The proximity to the bulbs was critical and I discontinued their use due to the fire hazard. They can have a desiccating, even a roasting effect, if not used very carefully.
Title: Re: Frost Protection
Post by: lebmung on November 27, 2019, 04:30:50 PM
I referring to the infrared bulb mentioned by lebmung. Will it work on an infrared heat lamp?

I was heating mu dog with that last winter 150W. It did pretty warm and the door can be open.
I think this os a solution for older trees that are cold hardy. So when a very low temperature come they will make it through. You need to measure the leaf temperature not to burn them. I will make a test when freezing comes.
Title: Re: Frost Protection
Post by: hardyvermont on December 08, 2019, 03:53:47 PM
My Home Depot has Thermo Cube as a seasonal item.  They had 4 and would not be restocking.  They are also available on Amazon. 
Title: Re: Frost Protection
Post by: will2358 on December 23, 2019, 05:09:36 AM
This is how I protect mine.  I am in zone 8a also, about 75 miles south of you.


(https://i.postimg.cc/dkWSZ1T3/1120181342b-HDR.jpg) (https://postimg.cc/dkWSZ1T3)

So far has worked fairly well.  I haven't lost a tree yet, though I have had some minor damage.


TFN
TFN were do you get the barrels? Do you fill them with water?
Title: Re: Frost Protection
Post by: poncirsguy on March 18, 2020, 09:36:55 PM
My cold protection setup.  On the left is my grafted Meiwa to kuharske citrange.  Middle picture left New Zealand lemonade on C35 roots. to the right Valentine pomelo on US897 root.  last picture is seedling Fukushu kumquat.  Structures come down after danger of frost has passed for my USDA zone 6a/b growing zone.
(https://i.postimg.cc/hzwSbRvc/IMG-0538.jpg) (https://postimg.cc/hzwSbRvc)

(https://i.postimg.cc/CB3Ljprk/IMG-0561.jpg) (https://postimg.cc/CB3Ljprk)

(https://i.postimg.cc/K47y9TRd/IMG-0560.jpg) (https://postimg.cc/K47y9TRd)
Title: Re: Frost Protection
Post by: SoCal2warm on March 20, 2020, 03:50:37 PM
Well, I haven't had good luck with my frost protection. It seems that enclosing the frame with transparent vinyl plastic leads to a greenhouse effect during sunny days, which can lead to the plant starting to come out of dormancy, and then the cold night comes and the temperature rapidly swings in the other direction. The daytime difference between inside and outside can be great, whereas the nighttime differences are only a few degrees. The hardy citrus does not handle these temperatures swings very well. Or at least that's what it seems like.

Probably would have been better to use an opaque white enclosure to avoid excessive heat build-up. Maybe even with a small vent on top to be able to leak out excessive heat.
Title: Re: Frost Protection
Post by: kumin on March 20, 2020, 04:44:21 PM
Increasing the air volume has a partial mitigating effect as it tempers the overheating problem a bit. White overwintering film with 55-70 % blocking is very useful in reducing overheating. As you mentioned, simply venting hot air to the exterior is immediately effective.
Title: Re: Frost Protection
Post by: poncirsguy on March 20, 2020, 07:10:58 PM
I need to add that the glass used on my enclosures are made of double sets of Low-E windows.  My enclosure does not heat up uncontrollable on bright sunny days.  The biggest enclosure has plane glass at the bottom so that what heat comes in heats the soil to aid in roots moving water as  needed.  It holds heat down to 15F over night so that plants don't see  frost.  There is also enough humidity so that the inner layer of 4 layers glass can keep from freezing through condensation and at last freeze-frost.  still locked at 32F until the humidity is gone.  That takes a long time.  Heat of condensation 520 cal/gram.  Heat of fusion another 80 cal/ gram.  I plan to use an open barrel of 60F water as a heat source to provide the humidity to provide my condensate freeze heating system when the final shape of  my greenhouse is determined.
Title: Re: Frost Protection
Post by: kumin on May 17, 2020, 07:17:04 AM
 https://www.as-garten.de/ueberwinterungszelt-igloo (https://www.as-garten.de/ueberwinterungszelt-igloo)



Of course, if you have some technical skills, you can reproduce this solution in these or other dimensions.

The geometrics of this protective enclosure are well designed. By narrowing the top exposure, wind and night sky radiant cooling are reduced. By maximizing ground exposure, warmth radiating from the soil is captured at an increased rate.

So for me, it appears to be based on sound theory. Actual field conditions may confirm, or refute the concept.

As I look at the photo in greater detail, I see there's a floor on the bottom. This would block the warmth from the soil. I believe this may not be as practical as I originally thought.

The design may be eye catching for marketing purposes. A bit like designing fishing lures to catch the eye of the angling customer more than the actual fish.