my above ground over-wintering structure

Whats a renter to do?

I have several hundred (I'd say between 3 and 4 hundred tree seedlings in pots, a few shrub seedlings too).
I made this contraption of a monstrousity of a thing in late Summer and a little into Fall. I'm just trying to minimize more the
bad results I had from last Winter when not trying any protection, just bare pots, and I paid dearly. Its a 12 foot long 2 x 12 in the front and several 2 x 8s down the sides (I think 3 on each side). I don't even know if it will help any, but I wanted to try it since I had the lumber and definitely the plants. Oh, and I threw some soil in there around some of the more marginal seedlings. And also a while back some scheister pulled the "unseen, dump some wood chips scam" on my Grandma's yard, so I spread a bunch of that over the top of everything with one full load in that modified red cart you see in the photos. Which is actually a lot, I made 2 foot walls all around that cart, it holds a lot with the walls in it.

I do realize that pots and plants need to be in the ground, but I am a renter, I can't alter anything and dig any holes, not even an inch. My Grandmother is my land-lady and she hasn't exactly been cooperative with me on my stuff outside.

Anyway, I took a few photos of this thing to share with anybody who wants to have a look. They are in my photobucket album, I'll post a link. -

http://photobucket.com/albums/v243/w4i0a/my%20above%20ground%20overwintering%20structure/?sc=6

Will

Shortleaf, I overwinter a lot of potted plants. The best way is to bury them but when you can not do that your system looks pretty good to me. My suggestion is to make sure all the plants are watered before everything freezes, then cover the entire area with leaves. I'm sure there is raking that was/needs to be done. Lots of leaves, 6 to 12 inches of them. They will settle a lot but most important is they will break the Freeze/Thaw cycle that does all the damage. Good luck.
I cover my buried potted plants with lots of leaves too!
Andy P

I'm 100% with Sarahskeeper. Break the freeze thaw cycle. If you can get your hands on some pine needles to layer in between the leaves, the leaves will be less likely to compact as much. I've also noticed that ever so often leaves will start their little decomposition routine and I have ended up with a few plants here and there that succumbed to fungal attacks. I wouldn't go out there sprinking sulfur powder or anything but I know you have pine needles around and maybe you could consider adding a whole new layer of pine needles over the leaves and then another layer of leaves sort of like a sandwich. I think your plants are wonderful, as always. I think they will all come out of dormancy just fine. There is one other added bonus to using pine needles as a layer, in the spring you can peel it off a lot easier than removing blankets exclusively of leaves. I swear it rolls right up like a carpet and you can just lift if off of your plants.

The other thing Sarahskeeper mentioned was watering them well before covering them up. I also think this is important. A winter drought can be far worse on plants than a summer drought. I have a system similar to yours that was a direct result of running out of time. I can dig holes here, I just had too many other things on my plate. I tried to get them in the sand box but the sand had already frozen solid. Next best thing was to place them in the sand box and "blanket" them. The first year I did this was last year which was actually a brutal year and everything survived. This year I did it out of pure and unadulterated laziness because I figured why dig holes when everything survived above ground and "blanketed" last year. I am relying heavily on pine needles though because I also learned that a blanket exclusively of leaves ultimately repelled rain and snow wherein which I do want some rain and snow to soak down to keep the plants from drying out over winter.

One other thought: if you have access to white plastic greenhouse sheeting, cover the whole thing after you water them and add the leaves. The plastic cover will seal it up from dessication, trap more ground heat, and keep the leaves dry and fluffy over winter. And try to blow in the leaves, so they're nice and loose.

Do not use clear plastic or black plastic, due to sun absorption. (If you have only clear plastic, I guess you could whitewash the underside like folks used to do with glass greenhouses.) You might also use shade cloth or floating row cover -- permeable, but better than nothing.

Guy S.

Clear sheet plastic is an excellent idea as is row cover.

No, not clear, unless you can shade it -- white.

Guy S.

Why not clear that is vented?

OK, but venting somewhat defeats the purpose of providing a sealed environment. You might have to remove the cover to water every month or so, and you lose a lot of heat during cold nights unless you manually adjust the vent each morning and evening.

Guy S.

Thanks for all your advice, it all sounds very helpful, I am glad to have it. It has already got down to about 5 degrees F, I should've already done that with some leaves, pine needles and plastic. Better late than never, I may try it yet. I have some seedlings like Water Tupelo, Oaks, native Missouri cactus, Mimosa and other seedlings that I didn't really want to expire this Winter, but it won't be the end of the world. I can easily grow a lot of it from seed. But some of the seedlings, like the Nyssa aquatica (Water Tupelo) I had to order a bare-root bundle of, from the state nursery, which is a bit of a project itself. Most of the green plant stuff that can be seen from the back is Austrian Pine, Norway Spruce and Eastern White Pine, their all evergreens, I don't have THAT much good luck keeping deciduous seedlings green! The closed end of the structure faces North, which I thought was best to slow down the North wind from whistling in there.

Will

I dunno Guy, I get the heevie jeevies thinking about trapped air covering a bunch of plants smothered in decomposing leaf material. It's that sealed environment combined with reduced light of an opaque sheet of plastic that is giving me visions of all kinds of fungi sparring to colonize underneath. I'm probably totally off base and you're probably 100% on the money as usual but I just get nervous whenever I can't vent something or let the sun's rays hit it to keep the nasties at bay. I'll go pick up a sheet of opaque white and try it this way next year. I've got oaks and hickories in the sand box as well as quite a few native grasses and sedges. I know I tossed other plants in there but for the life of me I don't recall what I tossed in there.

Will , the native Missouri cactus sounds interesting. Did you start that from seed or from cuttings?

I agree with the suggestion that clear plastic is a poor choice as a cover for plant material. It creates a passive solar collector & temperatures inside the enclosure are sure to fluctuate wildly. You're likely to see temps inside over 90 on sunny days. This will raise root temperatures & likely initiate new growth at very inopportune times (mid-winter e.g.), only for it to freeze when temps next drop.

About freeze/thaw cycles. They have little to no effect on rootage unless they are protracted & raise soil temperatures high enough for long enough to initiate growth. Roots can freeze & thaw daily all winter long with little ill effect unless one of the thaws stimulates the onset of growth. If that should occur, cellular cold-hardiness is greatly diminished, leaving the plant vulnerable. If the soil temperatures remain in the low 40s or lower, or if temperatures creep up to mid-upper forties for short periods (a day or 2), trees will likely remain dormant or quiescent, and unaffected by freeze/thaw. Later in the spring, photo-period also enters the equation here and has an effect on the onset of growth as the beginning of a new growth cycle approaches, but o/a, trees, including containerized trees, are not much affected by freeze thaw unless they begin growing.

Obviously, frost can heave containerized trees dug in for winter, and it can produce bark and sap/heartwood splitting problems, but the effect on rootage is pretty insignificant.

Al

Some commercial nurseries overwinter bare-root stock in large walk-in coolers that stay at 100% humidity and about 33 degrees. But that takes big bucks!

FYI, we overwinter our hardy container-grown plants in a white polyhouse built against the shady north wall of one of our outbuildings. We seal it up tight in late November or early December and keep it between 30 and 40 all winter, only venting and watering it in spring during warm days. We soak everything down, then blow in some dry leaves as a light mulch before sealing it (they stay dry and fluffy all winter), then don't touch it again until spring venting. Fine Gardening did an article on it about 15 years ago or so ("Building a Winter Home for your Plants" or something like that) -- boy, did I look young in those pictures!

Guy S.

Time will only tell with my structure. I remember last Spring, I waited in April, then May, then June, no growth from many of my plants, even some of my favorites. I had one Shortleaf Pine that I liked real well, it perished too. This year I still have Shortleaf Pines, but not as many. The ones that are left are the ones that came through last Winter, and I'm glad they did. This year, they are getting a little protection, on top of just being survivors. I couldn't do my name justice if I didn't have a Shortleaf Pine somewhere!
I was surprised at what lived, and what didn't last year though. It was a learning experience for sure.

My "native Missouri cactus", thats what I call them. Is I think Cylindropuntia and just regular Opuntia (Prickly-Pear). If I'm not mistaken their native. I know the Prickly-Pear is, I have seen it semi-commonly in parks and rocky out-croppings here.

There is 2 neighbors down the street that are growing Cylindropuntia. One neighbor has it in the ground, and the other neighbor has it in a big pot by his mail-box. They both have came through Winters and grew the next year.

One neighbor had a big pot of Prickly-Pear out by his mail-box, and I bought the big pot from him for $20. I now have the big pot outside. It appears to be dead on the top. I am guessing the Prickly-Pear will grow from the root system underneath next year. That same neighbor has the Cylindropuntia in a pot too. I gave him $10 to trim that pot all up and get the cuttings. I felt a little bad about getting all his Prickly-pear so I only asked for trimmings of the Cylindropuntia.

In short, my Prickly-Pear came "as-is" in a big pot, and my Cylindropuntia I am trying to propagate from cuttings.
I plan on starting them from seeds after I learn more about them, in particular, where the seeds are at! I'm pretty sure the PP seeds are in those red oval pods. The Cylindropuntia I'm not sure about yet. I've already propagated the PP earlier this year just by sticking pads in soil in pots, as you can see in some of the photos.
I don't expect them to take over from last year's growth above ground, like a deciduous tree.
I am guessing that it will die on top, but live on the bottom and re-grow quite vigorously the next year.
You know you're a gambling sort when you also have Banana plants (Musa basjoo) in North Missouri!
Although, I don't really gamble, like at a casino!

This will be my first year with both of them, so I'm gonna see how they do this Winter and next year. I think it would be really neat to have like a half barrel full of "Missouri native cactus" out in the front landscaping out just beyond the front porch of a house.
I took some more pics of my "Missouri native cactus". -
http://photobucket.com/albums/v243/w4i0a/missouri%20native%20cactus/

If everything works out right, I'll have some of my own land in Kansas in less than a year, and can do a better job with my over-wintering.

Thanks for the good advice all.

Will
One pot of a big cutting of Cylindropuntia in my over-wintering structure

Shortleaf, I'm uncomfortable with any plastic cover. Leaves/needles will allow the plants to breathe. What happens when the plastic gets weighed down with heavy snow?
I may have exaggerated the amount of leaves needed. The idea is to at least cover the pots, not the entire plant. I noticed the pots are black, black absorbs a lot of heat from the sun.
Andy P