Portable greenhouses

mcpesq817

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Does anyone here use a so-called "portable greenhouse" to overwinter their trees? Last year I used my detached, unheated garage (with a small window facing south so it gets some light) to overwinter my trees, but since the garage is insulated, it does tend to warm up quite a bit during those crazy "winter" days were temps are way up from what is expected. I ended up getting early bud breaks, and had to do the in and out shuffle during warm days and cold nights.

So, I was thinking about overwintering some of my trees (mostly my evergreens like JPBs, JWPs, junipers) outside in a spot that gets eastern protection from my house and southern protection from my porch, along with some northern protection from my neighbor's shed. I figured I would bury my trees in the ground and mulch them in, and erect some sort of wind screen. In looking for materials, I came across these portable greenhouses such as these, which could serve as an easy windscreen, moderate temps, and give some filtered sun to my evergreens:

http://www.greenhouseshowcase.com/Portable-Greenhouse-Green-Trim.htm

So, just wondering if anyone has tried these out and what your experiences have been in terms of the materials holding up, etc. I have a pretty small yard, so unfortunately the more permanent structure greenhouses are likely out of the question (unless they can break down pretty easily).

Thanks in advance!
 
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Does anyone here use a so-called "portable greenhouse" to overwinter their trees? Last year I used my detached, unheated garage (with a small window facing south so it gets some light) to overwinter my trees, but since the garage is insulated, it does tend to warm up quite a bit during those crazy "winter" days were temps are way up from what is expected. I ended up getting early bud breaks, and had to do the in and out shuffle during warm days and cold nights.

So, I was thinking about overwintering some of my trees (mostly my evergreens like JPBs, JWPs, junipers) outside in a spot that gets eastern protection from my house and southern protection from my porch, along with some northern protection from my neighbor's shed. I figured I would bury my trees in the ground and mulch them in, and erect some sort of wind screen. In looking for materials, I came across these portable greenhouses such as these, which could serve as an easy windscreen, moderate temps, and give some filtered sun to my evergreens:

http://www.greenhouseshowcase.com/Portable-Greenhouse-Green-Trim.htm

So, just wondering if anyone has tried these out and what your experiences have been in terms of the materials holding up, etc. I have a pretty small yard, so unfortunately the more permanent structure greenhouses are likely out of the question (unless they can break down pretty easily).

Thanks in advance!
For that amount of money you can easily design your own and have it more functional for your purpose. Keep your dimensions to fit your standard board lengths ie. 8 ft high 12 feet long and 8-10-or 12 feet wide. Use treaded wood. Staple gun 6 mil. plastic on your frame. You can cut a "window" out of the plastic for hot sunny days and then use duct tape to close the flap when it gets cold. Instead of using nails, use bolts and nuts which make breaking down the structure easy and can be stored until needed again. Number the boards so you can put it up and down easily. You get more bang for your buck this way. Your Pre-made shelter needs a way to have either a fan installed or a window that can be opened and closed. Check out how long the plastic will last... many types only good for two to three years before the either cloud up or become very brittle from the uv rays. Heat is the main problem... think of a car locked up in a parking lot during the noonday sun. These can be like ovens if kept closed up during a sunny day even if the outdoor tempts are very cold. Also think up front about the convenience of being able to get in and out and watering. You need to have a number of plants to store this way to make the expense and time worthwhile for the project. You can also utilize the space better if you have a 2" X 4" fence wire hanging down the center and you can hang all sorts of plants from this wire on BOTH sides of it. This keeps your ground and bench space free for other plants. Do you plant to heat this in the winter to keep the temps above 33 F ? Some times just having lights on inside your structure will raise the temps 5 to 10 degrees. One last thought.... disaster always strikes at two to three in the morning when it is windy and cold and raining or sleet. Alway something but it never happens at a convenient time when it is mild and sunny.

***PinewoodsBear***
zone 8 East Texas
 

capnk

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You will have much more trouble with the portable greenhouse overheating on sunny days than you have with the garage.

Overwintering outside, buried in the mulch, should be fine.
 

mcpesq817

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Thanks Capnk.

Is that true even if you keep the vents open on warmer days?

I've also thought about burying my trees under mulch under my benches, and on very cold days, wrapping burlap or some plastic wrap around the benches and on top of them, particularly to cut out the wind. But if I do that, then my evergreens won't receive much sunlight and precipitation (we tend not to get snow here in DC, but rather freezing rain). I know there is a difference of opinion out there on whether evergreens need sunlight or not, which is part of the reason I'm having trouble figuring out what I should do.
 

DaveV

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Mcpesq817, Yes I would think that even with the vents open on a warm sunny day it would really heat up inside the greenhouse. I use one here in Iowa in the spring, it can be 30 F outside and 70 F in the greenhouse with the vents open. You might want to try to place a black trash bag over the windows in your garage over the winter.
 

Attila Soos

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The solution for preventing overheating, is to keep all the vents open during the day, AND install a fan that is turned on during the day (I have a small fan that consumes so little electricity that I don't even notice on my bill). In addition, cover the greenhouse with a 30% - 50% shadecloth.
These 3 easy things together would keep the greenhouse cool. You can also keep the door/main entrance of the greenhouse partially open, along with the vents, which will definitely keep the air moving in and out.
Then, during the night, close everything, to prevent freezing.
Just keeping the vents open is not enough. But with the two additional measures, there is no problem.

Plus, you can use the greenhouse to rehab freshly dug trees, and for propagation - this way over time, it will pay for itself.
 
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mcpesq817

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Thanks Dave and Attila for chiming in. I'm sure I've driven one friend particularly crazy with all my overwintering questions, so I figured I would get insights from others to spare him the pain :D

I guess my thought process with the portable greenhouse is to keep the doors and vents completely open all day, and just zip things up on very cold nights or during windy days. Dave, that might address the overheating issue you mention. I guess I don't see how the portable greenhouse is really any different than using a more permanent greenhouse structure, or using hoop tunnels and the like.

These are the various pros and cons that I see with various overwintering methods:

1. Garage - not much light for evergreens, tendency to stay on the warmer side, which might give me issues with giving my trees enough dormancy.

2. Mulch outside under benches with burlap windbreaks - on really cold days, I could have problems with the temp inside the storage area dropping considerably. On the positive side, cheap to install, and I would still get some sunlight and precipitation.

3. Mulch outside under portable greenhouse - temps could be warmer than desired. At the same time, I would have an easy mechanism for windbreaks and keeping freezing rain off my trees.


So I think I'm leaning towards deciduous and more sensitive material in the garage, where I can use a space heater on really cold days. My evergreens will go outside under options 2 and 3. Ponderosas will just be on the ground under mulch with no protection.
 

Attila Soos

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Thanks Dave and Attila for chiming in. I'm sure I've driven one friend particularly crazy with all my overwintering questions, so I figured I would get insights from others to spare him the pain :D

I guess my thought process with the portable greenhouse is to keep the doors and vents completely open all day, and just zip things up on very cold nights or during windy days. Dave, that might address the overheating issue you mention. I guess I don't see how the portable greenhouse is really any different than using a more permanent greenhouse structure, or using hoop tunnels and the like.

These are the various pros and cons that I see with various overwintering methods:

1. Garage - not much light for evergreens, tendency to stay on the warmer side, which might give me issues with giving my trees enough dormancy.

2. Mulch outside under benches with burlap windbreaks - on really cold days, I could have problems with the temp inside the storage area dropping considerably. On the positive side, cheap to install, and I would still get some sunlight and precipitation.

3. Mulch outside under portable greenhouse - temps could be warmer than desired. At the same time, I would have an easy mechanism for windbreaks and keeping freezing rain off my trees.


So I think I'm leaning towards deciduous and more sensitive material in the garage, where I can use a space heater on really cold days. My evergreens will go outside under options 2 and 3. Ponderosas will just be on the ground under mulch with no protection.
Sounds like a good plan :).
 

rockm

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From the crazy friend:D:D--I would not use a portable greenhouse for overwintering here in the D.C. area. It's not necessary and will likely add more problems than it solves.

Polytunnels with open ends, or a plastic cold frame, placed over a mulched cold pit are a much less expensive and more reliable option. Aside from the cost advantages, there's also less of a danger in overheating and you don't have to constantly worry about opening and closing vents--I used to worry extensively about opening and closing the covers on my cold frame, but gradually, I noted that it didn't make much difference to most of my trees. I eventually decided to leave one sheltered side open and the other closed--which shed excessive rain and prevented ice build up. This solution has worked for the past 10 years or so. Also for what it's worth, I've left my scraggly Japanese black pine out on the bench unprotected for the last 8 winters. It's still alive.

Something as simple as this:

http://doorgarden.com/03/plastic-tunnel-cold-frame-row-cover

placed over a 10 inch deep excavated bed mulch level to surrounding soil and with ends left open ALL WINTER can protect even trident maples in this area.

If you have plastic shelving, it's even easier--dig the 10 inch deep pit, put the trees in, mulch, put te benches over top, cover with heavy duty plastic sheeting--leaving two ends uncovered...

Oh, don't take overwintering advice from Californians...:D:D
 

Attila Soos

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Shut up...:)

(BTW, I used to grow bonsai in Vancouver before I ended up here)
By the way, I have to admit that I am a little biased, when it comes to greenhouses. I only recommend it if one plans to use it for more than just strictly overwintering.

Since I was a kid, and growing up in a cold climate, a greenhouse was the realm of exotic, where one could create a whole new world and grow stuff from far away lands.

So, greenhouse is for those who like to experiment, try out new things, learn more about how climate affects plants, etc. If one just wants to get over the winter, there are other simple and practical (and cheaper) alternatives, as Rockm mentioned.

(My goal is that one day, when I can afford it, build a giant greenhouse, and create a climate similar to the cool cloud forests of the tropical mountains...or, the alternative would be to retire in Hawaii and live in a hut on a REAL mountain cloud forest).
 
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greerhw

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Depending on where you live, shade houses can be a better investment that green houses. in the summer months when the temps reach 100 degrees, they are better than natural shade, depending on the amount of sun you want to pass through. In the winter months, I cover mine with co-poly to block out the UV rays, and heat it with a quartz heater never letting it get below 34 degrees. This works well for me in Oklahoma.

keep it green,
Harry
 
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Rick Moquin

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Depending on where you live, shade houses can be a better investment that green houses. in the summer months when the temps reach 100 degrees, they are better than natural shade, depending on the ammount of sun you want to pass through. In the winter months, I cover mine with co-poly to block out the UV rays, and heat it with a quartz heater never letting it get below 34 degrees. This works well for me in Oklahoma.

keep it green,
Harry
Yup! This one is in full sun and they absolutely love it. Gable are screen.
 

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Tachigi

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My goal is that one day, when I can afford it, build a giant greenhouse, and create a climate similar to the cool cloud forests of the tropical mountains...or, the alternative would be to retire in Hawaii and live in a hut on a REAL mountain cloud forest.
I got dibs on the guest bedroom...or grass mat...hell I'll take the Hamock:cool:
 

Attila Soos

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... and the difference would be?
I know, for those from Quebec, Vancouver is a tropical paradise :)
But for Southern Californians, it's a winter wonderland.
I do remember though, that for about 2 or 3 weeks, in January or February, my bonsai were frozen solid. They looked as if they had glued-on gravel on top. But that's because I lived 5 minutes from the beach. For those living 50 miles inland, they had some real cold.
 
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mcpesq817

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(My goal is that one day, when I can afford it, build a giant greenhouse, and create a climate similar to the cool cloud forests of the tropical mountains...or, the alternative would be to retire in Hawaii and live in a hut on a REAL mountain cloud forest).
Are you adopting by chance? :)
 

treebeard55

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I find I can make an adequate shelter quite cheaply with some old lumber, concrete blocks, and a "spun-bonded" fabric (made for covering coldframes, that sort of thing.) Of course, it helps that my back yard is very well sheltered from wind.
 

mcpesq817

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Thanks very much to everyone that chimed in.

One more question - I have a really bad problem with rabbits in my neck of the woods. They seem to indiscriminately chow down on anything that is near ground level. I was thinking of going with Rockm's suggestion of either creating a hoop house thing like in his link or just covering my benches with plastic film, but was worried that rabbits or some other critters might decide to nest inside.

By the time I set up my overwintering quarters (around Thanksgiving), are rabbits and other critters already hibernating? I wasn't sure whether they would bury down under the plastic, even if I tied down the plastic or put cinder blocks down. Unfortunately I can't really build a more permanent structure because I don't really have the space and a shade house won't really look all that good in the area I'm thinking of - won't pass the WAF test (wife acceptance factor test).
 
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