Potted Maples and the Vortex

Discussion in 'Maples' started by Kaitain4, Feb 8, 2014.

  1. Kaitain4

    Kaitain4 Well-Known Member Maple Society 10 Years

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    So this winter has been especially brutal here for us in the South, where we do not normally experience temps below the teens - and then only for brief periods (as in hours). Our winters are generally mild (30's t0 50s). But this year we've had sub-teen weather for days at a time, and repeatedly so. I'm concerned about my potted cultivars and root death. With well over 100 trees in pots, and several hundred grafts in pots and trays, I'm not sure what to expect come spring.

    Any real-life experiences with these conditions and potted maples? Please share!

    Thx
     
  2. AlainK

    AlainK Generous Contributor Forums Moderator Maple Society 10 Years

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    Hi,

    I used a Farenheit-Celsius converter and I understand that 30-50 F means 10°C to -1°C, is that correct?

    I don't really understand what you mean by "sub-teens", but here, we usually have a few days of temperatures around -5°C at night, sometimes a couple of nights around -10°C. If the soil doesn't stay frozen too long, there's usually no pb.

    In the winter 2011-2012, we had a long spell of very cold weather at the end of the winter, and many here in Europe lost trees: on top of the damage caused by the cold, the weakened trees caught diseases, and I even lost trees thet were in quite big pots.

    Since I don't have a greenhouse, I protect my seedlings and trees in smaller pots (I'm into bonsai ^^) by putting zelkova leaves (they don't have any diseases, and I have a big one in my garden) to the first branches, or pine bark.

    Here in France, we've had the mildest winter since the 1880's, so the only thing is to make sure that the pots drain well because it's rained a lot.

    Some of last year's Acer buergerianum have already pushed ou new leaves, and my Iris reticulata that flowered in late March last year already display their colours!

    Here are a few pictures I took last week (Acer b., Iris r., and Prunus serrulata 'Accolade'):
     

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  3. NJACER

    NJACER Active Member Maple Society 10 Years

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    K4,

    As you know, I have lots of plants in pots that I winter over in a cold frame. This structure protects them from wind but not the cold. I have very few losses in this situation.

    I also keep many pots outside unprotected and have mixed success with these. Last year I was busy with hurricane Sandy clean up and did not get to my nursery area to winterize. I left 180 1 gal maples up on plastic pallets that I use in the summer and spring for easy of care. All of these were lost last winter. Almost every pot that was stored on the ground survived. This year has been exceptionally cold. Only spring will tell. Lesson learned. Keep the pots on the ground and protect them from the wind and sun scald.


    Ed
     
  4. Kaitain4

    Kaitain4 Well-Known Member Maple Society 10 Years

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    Alain and Ed,

    Thanks for your replies. Ed, that was really interesting about the pots touching the ground being the ones that survived. I hope that turns out to be the case for me!
     
  5. Daniel Otis

    Daniel Otis Active Member Maple Society 10 Years

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    I have mixed experience with leaving potted maples outside over winter, here where in a typical year winter temps fall to 15 F below zero (-26 C). For several years I buried 50 or 60 pots every year--buried the pots completely, and piled up the soil over the top a bit. A big pain, but I don't think I ever had a loss among these trees--the warmth and insulation of the soil kept them safe.

    I also, one year, left a dozen or so A. buergerianum outside all winter, bone-dry, above ground, in small pots that had fallen on their sides. They were considered marginally hardy here, so I assumed they wouldn't make it--but they all survived. I've wondered if the dry soil contributed to their survival.

    And then, one year, I left many of my maples outside over winter, in pots standing upright above ground with no shelter. I don't know what the temperature fell to, but it surely reached 0 F for a succession of nights. I lost more than half of my palmatum cultivars, I would say.

    My guess, given your situation, is that you may lose a few, but probably fewer than you fear. I would expect survival to vary by cultivar (in my experience, Koto hime, for instance, is not at all hardy). If they were frozen solid at 10 F for days at a time, you may well lose some. But it will also vary by the time of year of the extreme cold, rootstock, how well-watered they were when they hit the cold, whether it warmed appreciably during the day, how large the pots are, their specific location, whether there was any snow cover, and probably other factors too.

    Well, I hope they make it. Do let us know what happened, once the tally is in. I bet you'll be surprised by how many survive, and I wouldn't be surprised to hear that they all make it.

    D.
     
  6. maplesandpaws

    maplesandpaws Active Member

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    K4 - This is the first time I have over-wintered all my pots outside, and of course it would be the coldest one since I moved here in 2007. I have had about two dozen potted maples and conifers, from 1g all the way up to 10g, sitting on the concrete patio under the deck this winter. Most of my maples are also in the fabric pots, which (I think) makes them even more susceptible to cold temps. I dismantled a resin shelving unit and placed the smaller fabric pots onto the shelves so they weren't sitting directly on the concrete; the shelves were also placed on a layer of leaves, thus providing just a little extra insulation. For the pots that didn't fit on the shelves, they too were placed on a thick layer of leaves; I then piled leaves all around and over top of the pots. When we had the bitterly cold snaps, I managed to jerry-rig some t-posts such that I could drape some sheets over top to provide a little extra shelter, especially from the wind.

    I just checked on everything and I am quite pleased with how good the trees look - I see very little, if any, evidence of die-back on them, and the buds look nice and healthy. Obviously, leaf-out later this spring will be the true tell if any damage has occurred, but at this point I am quite optimistic. I hope this will end up being the case for you as well. :)
     

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  7. Schattenfreude

    Schattenfreude Active Member

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    K4 and Andrea,

    How did your trees survive last winter? Please give us an update on what didn't survive the brutal cold of last winter.
    I had 4 trees in large pots in an unheated garage, sitting on the concrete floor and all came through the winter, but I must admit, didn't seem to flourish over the summer. This time around, I went ahead and dug large holes for them and buried them like I do with my smaller pots. I'm not nearly as nervous as I was last year :-)

    Kevin in KC
     
  8. maplesandpaws

    maplesandpaws Active Member

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    Kevin,

    I had very good success with my set-up last winter, and have repeated it this winter. Regarding the maples, I had a little tip die-back on a few smaller trees, and I only lost one - Squitty, which is a more sensitive cultivar to begin with. I did lose one Japanese white pine (2g pot, but the tree itself was not very big), and my weeping spanish cypress (this was in a very small pot, and should have been kept in the garage, not outside).

    This year, instead of covering the trees as shown in the pictures above, I simply hung sheets all around the deck, so the whole area can be enclosed. Because the sheets still breathe, unlike plastic (tarps, etc), I still get air movement, but they also block the wind and help keep a little extra heat in. What I did change this year is instead of having some of the smaller pots - including conifers, pieris, azaleas - under the deck, I have them in carts that I can wheel back into the garage if things get too cold (like the past couple of weeks). So far, knock on wood, things look good. :)
     

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