Over-wintering bamboo/ other plants

[stevelau1911]

Is it better to keep the snow on top of the greenhouse for extra insulation even though it's blocking light, or would it be better to clear the roof so it can heat up?

I'm thinking "clear the roof", but don't really know.

Last year I kept cleaning it off until I realized that leaving the snow on actually makes the greenhouse act similar to an igloo which prevents night time temperatures from getting that cold. So far, the coldest it has reached outside is around 21F and the greenhouse temperature has stayed at 33F. There is also very little sunshine during the winter months around here. The moso grove is also positioned on the west side of the greenhouse to create a snow drift which will hopefully reduce the winds and add insulation.

I've also learned last year that the in-ground bamboos that are completely smothered by over 1ft of snow by now do not mind it since they should be in complete dormancy from December through February.

[needmore]

That snow can crush your greenhouse frame quite easily, so the first thing I do after a snow is clear it off the roof.

[stevelau1911]

It can if I let it keep piling up, but I've reinforced the aluminum pipes to allow it to hold more weight. The blunt of the snow fell when it was in the lower 20s so it is pretty light too. I usually brush off the snow when there is a lot of the heavy stuff.

If we get a few sunny days in a row, I will make sure the south facing side doesn't have that much snow so the greenhouse can heat up a little bit.

It looks like teens and possibly single digits in the next couple weeks and I haven't tarped any of my 19 month old in-ground mosos yet so hopefully the snow will protect them for now.

[foxd]

I have sometimes wondered why nobody seems to build greenhouses using a catenary curve shape for the hoops. It would seem to me that this would be better at supporting a snow load.

[Alan_L]

You mean inverted catenary curve, right? Maybe because a catenary arch is the ideal curve for an arch which supports only its own weight -- not the case here. But probably the main reason is they're harder to manufacture than a simple circular bend.

[Alan_L]

I've finally got some photos of my horizontal and covered plants. These are big pots -- most are 20 gal squats -- so we'll see if I have the same success that others (like Brad) have had using a similar technique with smaller pots.





More photos here:
http://www.itsnotworkitsgardening.com/2 ... lants.html

And the whole process posted here:
http://www.itsnotworkitsgardening.com/2 ... mboos.html

[needmore]

I went a different route this year, I buried the pots in a pile of leaves then hosed that down severely to compact the leaf mass. Left them all standing upright in their pots. Thus far they look fine but I already have about 100% leaf burn to in-ground Pl simonii, have not checked the other tender ones, wouldn't be surprised to see the moso leaves burned up when I check.

[foxd]

You mean inverted catenary curve, right?

Yes, the inverted catenary.

Maybe because a catenary arch is the ideal curve for an arch which supports only its own weight -- not the case here.

But thinking about it, even if the catenary arch isn't the ideal curve for a greenhouse, it has got to be closer to the ideal curve than a semicircle. Even with no snow a hoop greenhouse is under forces that make it want to cave in.

But probably the main reason is they're harder to manufacture than a simple circular bend.

Maybe, but perhaps nobody has thought about this before.

There is a modified or unweighted catenary curve that might work.
http://www.ams.org/notices/201002/rtx100200220p.pdf
Doing a quick skim of the paper it looks like a parabolic curve might be better for supporting a snow load.

Then again both the catenary and the parabola would raise the snow load up higher which would make it easier for the curve to fall sideways.

Perhaps greenhouses should use a paraboloid shape.

[stevelau1911]

I decided to over-winter all my bamboos yesterday so here are some of the pictures.

YG


atrovaginata


bissettii


Dulcis


parvifolia


This is my latest blog on overwintering bamboos. http://stevesbamboogarden.blogspot.com/ ... .html#more

[stevelau1911]

One of the things I learned after the tarp on my atrovaginata nearly blew off when we had the very high winds is to do a thorough job in tightening the strings, and not have the tarp so high up on the culms so that it can slide off. The branches point upwards so there's much less of a chance in the tarp sliding down as opposed to sliding up.

Here's the first attempt to tarp the 13ft grove.

Here's the tarp almost falling off.

Here's the tarp tightened all the way.

[Ego1607]

One question about tarping. Is it possible to overdo it and strangle the boo? I have P. Nigra tarped with an insulating material that looks like a thin dense cloth. It's realy warm and fluffy, but quite easily torn by the wind. I'm considering covering everything with another layer of thicker plastic foil, but i'm not sure if that could prevent the plant from exchanging gasses propperly or making the interior soggy and causing rot.

Anny sugestions?

[stevelau1911]

When the soil temperature is too cold for the bamboos to produce new leaves, I don't think they need any light or air ventilation at all. I think the only way to make the leaves rot is to bury the culms under a few feet of manure, and over winter they still might survive. If you are zone 6 or higher, I don't think you need anything thicker than overwintering film or shrink/ stretch wrap to protect the foliage. I would suggest tarping to the ground if possible, but if not, shrink wrapping all the culms together should provide some degree of protection.

I used only transparent either white or clear tarps for all of mine, never exceeding 1 layer so they do get a little bit of light over the winter, but I don't think they need it at all. The vertical tarps don't provide much temperature protection, but when there's light leaf burn, it doesn't take much protection to produce no leaf burn, and so far with a zone 7a winter, anything that is under a tarp of any kind shows no damage at all while the test culms generally have some leaves that show a bit of leaf burn. It doesn't look like these tarps have served much of a purpose so far this winter where it has only reached single digits twice.

[Ego1607]

When the soil temperature is too cold for the bamboos to produce new leaves, I don't think they need any light or air ventilation at all. I think the only way to make the leaves rot is to bury the culms under a few feet of manure, and over winter they still might survive. If you are zone 6 or higher, I don't think you need anything thicker than overwintering film or shrink/ stretch wrap to protect the foliage. I would suggest tarping to the ground if possible, but if not, shrink wrapping all the culms together should provide some degree of protection.

I used only transparent either white or clear tarps for all of mine, never exceeding 1 layer so they do get a little bit of light over the winter, but I don't think they need it at all. The vertical tarps don't provide much temperature protection, but when there's light leaf burn, it doesn't take much protection to produce no leaf burn, and so far with a zone 7a winter, anything that is under a tarp of any kind shows no damage at all while the test culms generally have some leaves that show a bit of leaf burn. It doesn't look like these tarps have served much of a purpose so far this winter where it has only reached single digits twice.

Thank you!
I'll see how this tarp holds up in the wind, and will probably add another layer of stronger material if any tearing occurs.

No tarping has been actually nececessary here also, as temperatures never went bellow -10°C (14F). Still, that's what I thought last year, just days before temperature suddenly droped to 0F top killing most od my plants. Better safe then sorry

[stevelau1911]

Just in case you were wondering, that thin frost cover blanket material completely blew off of whatever I used it on last winter, and basically ripped, or dis-integrated from the winter conditions so I would not suggest using that thin stuff. Luckily, there were no extremely cold temperatures last winter so that didn't matter too much.


Here's a form of winter protection that I am experimenting with this winter. I basically tied all the culms together with string, and then applied a layer of shrink wrap on my 14ft tall parvifolia. The top branches are left open to see if this shrink wrap does eliminate leaf burn if it ever occurs this winter.



It would not be hard to add Christmas lights if this happened to be a less hardy species of bamboo. This setup is feasible no matter how tall the clump gets given there is a tall enough ladder. Of course it would be much easier to do with one of those huge plastic tarps with grommet holes, but a 14ft tall bamboo doesn't require that.

Here's the grove before it got tied up.

[dependable]

Even with the open top, I would wonder if you might get some greenhouse effect w clear shrink wrap. I guess you will find out. The other thing I was wondering about last years pictures; Do the bags of leaves end up being rodent shelters?