Greenhouse/frame Covering ??

[sbarnhardt]

I've built myself a small frame/box to winter my trees in. It's approximately 5 ft long by 4ish wide. I don't remember the exact width and it's outside in the cold, dark morning and I'm inside where it's warm with a cup of coffee so I'm not measuring it right now. It's my first attempt at something like this so please take that into account. ?? I've used pex and pvc pipe with electrical conduit wall straps on the side of the wooden portion of the box to anchor the ends of the pipe to form my "hoop/roof."

I'm to the point of getting plastic to cover it. The first, and probably the cheapest, is to buy clear poly from Home Depot, or similar. I have read a blurb or two that discusses whether or not to go to the expense of buying film designed for a greenhouse as opposed to regular poly. I'm wondering if anyone has any recent experience with this and has any "wisdom" to impart on the subject.


** This time I think I have relearned thumbnails as opposed to large pics. Should be easier to look at now, maybe. I've added a reply with thumbnails in place of the pics that were here.**

 

[JudyB]

Clear poly isn't your friend on a winter storage house. This will just make it hot on sunny days, and you may have problems with keeping trees dormant. I would look for an opaque film, or if you have to use clear poly, I think there is some sort of greenhouse paint like product that you can coat the plastic with.

 

[Brian Van Fleet]

I made one of those when we first moved to Birmingham, and used it for part of the first winter. I found that, even with opaque plastic, interior night temperatures were the same as outside night temperatures, and daytime solar gain pushed temps into the 80s, when the outside temp was in the 30-40s. It required me to open it daily, water everything more often, and created fungal problems. I learned it was too cold for tropicals, and not necessary for temperate trees.

Since then, I just mulch everything in under my benches with pine straw. Our climates are similar, so it may be a solution for you as well.

 

[sbarnhardt]

Brian, Judy............ Thanks for your response.

I thought clear poly simply because that's what I see large commercial greenhouse around here covered with and figured that was what should be used. I'd planned to permanently fasten the plastic to the ends and the sides/top plastic to be on another piece of pvc or 2x2 treated wood so it could be rolled/pulled over the top as needed or just left open. Figured it would be as much use as a shield against wind, etc. as anything else.

I was planning to use pine needles as bedding material because it's easily available close to me at about 5 minutes to go there buy a bale and get back home. One of the benefits of living in a small town with a nice, long standing farm supply store.

So do you folks think I should just bed the trees in the box with pine needles and let it go at that? My only first hand knowledge and exposure to a serious bonsai artist was at Randy Clark's place in Charlotte before he moved to Florida. He put some of his trees in his greenhouse and some he bedded in pine bark in a wooden box similar, but larger, to mine under his shade structure/work shed.

This "is" my first attempt at this and I want to do it right.

As folks say in ham radio conversations..."I'll be standing by."

 

[Dav4]

I made one of those when we first moved to Birmingham, and used it for part of the first winter. I found that, even with opaque plastic, interior night temperatures were the same as outside night temperatures, and daytime solar gain pushed temps into the 80s, when the outside temp was in the 30-40s. It required me to open it daily, water everything more often, and created fungal problems. I learned it was too cold for tropicals, and not necessary for temperate trees.

Since then, I just mulch everything in under my benches with pine straw. Our climates are similar, so it may be a solution for you as well.

Boom! There it is....

If you do opt to use the structure, I'd leave it open ended for ventilation. It will still provide some protection from wind and cold, but the heat gain will be minimized and fungal issues will hopefully be decreased as well.

 

[JudyB]

If you were in a colder zone, I'd be sending you links to the materials that I like, but your zone is so different than mine...
I think your idea of a windbreak is good, maybe you could still use your framework to create a knee wall around the trees that you mulch in. Then perhaps cover the top if you really want with a shade cloth, (or maybe frost cloth) something porous that water will be able to get thru to water naturally. I don't know if you get snow, but it'd need to stand up to that. If this is sited in a sunny spot, you'll need to figure out something to block the sun.

Just saw Dav4's post above, looks like folks in your zones know what to do. Maybe you can use your structure for starting early tomatos! Now that you'd want clear poly for...

 

[Dav4]

I have always advocated the KISS method for overwintering. Too many people over think things, inadvertently complicating something which is really not complicated. The goal in overwintering temperate trees is to have them enter dormancy and stay that way until it is safe to start growing again, and that's it For me, in my location, I can leave most of my trees on their benches through the winter. The typical night time lows only fall into the mid to upper 20's F, and the sun is very low in the sky and doesn't really warm things up too much...consistent moderate cold is good at keeping trees dormant and that's what we want. Still, I'll have to place the trees on the ground once or twice during the winter if temps are going to fall into the teens. Last winter, we had lows fall into single digits 4 times...all the trees spent a few weeks on the ground and had leaves piled around the pots for insulation. Depending on things specific to you, including your ability to place trees on the ground and mulch them on short notice, you may want to pre-emptively mulch them in for the coldest part of the winter, and pine straw or wood chips is fine. Ideally, the location you choose will be out of the wind and sun.

 

[MidMichBonsai]

My area (Michigan) is much colder than yours and what I have done in the past is to place all of my trees on the ground, mulch around them with pine straw, and then surround them with about a 2.5-3 ft. burlap surround. This functions as a wind break from freezing winds and still leaves them open to getting snowed on and thus watered.

Even with the extremely severe winter we had last year (a 3 week period where it never got above 10 deg. and was often below zero) all of my trees emerged happy and healthy in the spring. I would suggest using your current structure, like Judy said, to create a knee-waist high wall of burlap and leave the top open. That way, your watering is taken care of naturally.

Most of the commercial greenhouses that you see with clear poly have circulation (fans) control and many have temperature and moisture control as well. Without that, as Brian said, you have very little say as to what happens inside based on sun and temp. changes and what was intended to help the trees ends up being a daily swing of extremes that really "puts them through the ringer".

As has already been said, simple is better.

Best!

 

[M. Frary]

Im in a colder climate than even mid mich. I basically do what he and BVF do and mine came through last winter none the worse for wear. I don't know how many days in a row below zero with wind chills down to minus 30. I know. I work outside every day. It's snowino right now.

 

[Eric Group]

Tree dormancy has a lot to do with the light as well... Clear plastic is not really necessary. Light is not needed once they go dormant, and the trees start going into dormancy even during summer once light starts to decrease...

For your climate- I am not completely familiar with your climate mind you, just assuming you are similar to some people I know who live close to you- there shouldn't be but maybe a couple nights a year when temps fall well below 20F for extended time when a cold hardy tree might be in serious danger of damage.

I would say on those nights you might want to consider additional measures, but for most of the winter, mulching around the base and maybe sticking them under a bench or an overhang of your roof to keep the frost off should be fine.

I VERY rarely get that kind of weather at my house, but I just stick the sensitive trees in my garage when it does come, the rest of the winter my trees stay pretty much unprotected...

What kind of trees are you talking about BTW?

 

[DougB]

Sbarnhardt what species trees will you be overwintering? My greenhouse even in winter often gets over 100F in the day and below freezing at night (I am in sandhills where I40 and I95 cross). Many if not most in our area winter their trees on the ground, often in the shade and mulch them in -- protecting from wind and sun and being able to water when necessary.

By the way The Triangle Bonsai Society meets on this Sunday -- join us. Arthur Joura is our special guest. http://www.trianglebonsai.com/

 

[Mike123]

suggestion

Just throwing this out there, you can set it to a desired temp. To open. $26.00.

 

[sbarnhardt]

Sbarnhardt what species trees will you be overwintering? My greenhouse even in winter often gets over 100F in the day and below freezing at night (I am in sandhills where I40 and I95 cross). Many if not most in our area winter their trees on the ground, often in the shade and mulch them in -- protecting from wind and sun and being able to water when necessary.
http://www.trianglebonsai.com/

For the most part, I have a number of JBP seedlings that I bought and potted earlier in the spring/summer. These are all in small nursery pots. I've got a couple of pitch pine seedlings 1-2 foot tall plus pot, that were harvested from the pine barrens of New Jersey, a couple of small hollies, a Japanese Wisteria, a Hinoki Cyprus, and an ilex crenata. Everything I have right now is in nursery, or similar, pots. I have nothing in bonsai pots.

After reading all these comments, I'm thinking I'd be better off mulching them with pine needles and leaving the top open with maybe, as someone said, a burlap wind break around them.

As far as cold goes here, you never know. We've had winters where you hardly knew it was winter and we'll sometimes have them where it gets cold (low/mid 20s to low 30s) and stays that way all winter. With a week or two of a bit colder than that on occasion. Snow is an iffy thing here. It can range from an occasional dusting all winter to one, or two, 2-8 inchers, usually in the lower range of that. What we do get, at times a lot, is ice. We get a lot of freezing rain with some significant ice build up. Maybe use the structure to cover them with a blue tarp, or similar, when significant ice is forecast?? I could do that leaving the burlap windbreak in place.

 

[M. Frary]

With winter always hope for the best weather but prepare for the worst.

 

[sorce]

You built such a nice frame. Id cover all but the usual downwind side with poly and call it one.

Sorce

 

[sbarnhardt]

Hopefully thumbnails instead of big pics this time. I had "forgotten" how to do it. Didn't think it had been that long since I'd done it. Or, to be quite honest it could have been "old age."

 

[Oliver Muscio]

Very nice frame. I agree heating in the sun could be a major problem, depending upon location. Here in Kentucky, I overwinter my outdoor plants in three locations: (1) mulched in the pathways between raised vegetable beds (for the most cold-hardy) BTW, we often have below 20 deg(last winter around 0, even) temperatures with little or no snow cover; (2) in an unheated shed; and (3) in a shelter with a pvc pipe frame covered with clear poly. This shelter is in a corner of our patio next to the house in a location that gets little or no direct sun during the winter. Although the poly is closed around all sides of the frame, it can be opened on warmer days. I keep the smaller and/or less harder trees here, as well as a few evergreens. Works for me.
Oliver

 

[Great Falcon]

how about tropical

Tree dormancy has a lot to do with the light as well... Clear plastic is not really necessary. Light is not needed once they go dormant, and the trees start going into dormancy even during summer once light starts to decrease...

For your climate- I am not completely familiar with your climate mind you, just assuming you are similar to some people I know who live close to you- there shouldn't be but maybe a couple nights a year when temps fall well below 20F for extended time when a cold hardy tree might be in serious danger of damage.

I would say on those nights you might want to consider additional measures, but for most of the winter, mulching around the base and maybe sticking them under a bench or an overhang of your roof to keep the frost off should be fine.

I VERY rarely get that kind of weather at my house, but I just stick the sensitive trees in my garage when it does come, the rest of the winter my trees stay pretty much unprotected...

What kind of trees are you talking about BTW?

what do you do with your tropical trees? do you have any? i'm a little over an hour from you.

 

[coh]

The goal in overwintering temperate trees is to have them enter dormancy and stay that way until it is safe to start growing again, and that's it

Well, that...and protecting them from all the varmints that want to eat them. If it's safe in your area to put them on the ground and cover with mulch, that's great. Around here that would be an invitation to a feast for all the voles, mice, rabbits, etc.

Chris

 

[sbarnhardt]

what do you do with your tropical trees? do you have any? i'm a little over an hour from you.

Nothing tropical right now!!