Overwintering plants in clay pots

Discussion in 'HortForum' started by torbie, Aug 9, 2006.

  1. torbie

    torbie Active Member

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    I'm fairly new to gardening and have a west facing balcony, that gets some light and wind from the south. Right now I have in clay pots, lavender, rosemary and just starting out with some catnip from seed.

    I just read somewhere that clay pots will break in the winter time, I'm not sure about the weather in Vancouver, will it get cold enough over the winter to break the pots?

    If anyone can let me know what they think that would be great! If I had to bring the plants indoors, they would be in my south facing livingroom and what, if any, special care would they need?
     
  2. Rima

    Rima Active Member

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    You need to know the quality of the pots - if they were 'high fired' vs 'low fired', which means the kiln temperature and time it took to cook them. You obviously can't know off-hand about most mass produced ones at garden ctres, but you can spend money for Japanese pots, known to be generally of better quality compared to some other well known Asian country's pots (all things being equal), you can mulch your pots very well (hard to do on a balcony tho'), and you can use (for small plant pots) big window boxes, just on the deck, with a layer of mulch on the bottom, the pots set down (not touching) and lots of mulch all around them. If you can rig some kind of windbreak against the NW wall of the balcony, strong enough so your worst winds won't send them crashing all over, do it (the plants won't need much sun til March).
     
  3. torbie

    torbie Active Member

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    Thank-you Rima, for your reply! The pots are just the cheap ones at the garden centre, made in Italy. The window box with the mulch sounds like an idea I could go with. They will be tucked into the NW corner, as there is an overhang, so they can stay a bit dry. I have seen the winds rip through and will find something to buffer that too.

    So much to learn, even with a small balcony! Thank-you again for your response.
     
  4. Rima

    Rima Active Member

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    Don't be afraid to let it snow on them.. great insulation!
     
  5. torbie

    torbie Active Member

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    I'm originally from NB. Here in Vancouver they consider a snowstorm anything over two or more centimeters :) Our winters consist of rain. Cold rain...lots..
     
  6. Ron B

    Ron B Paragon of Plants 10 Years

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    Untreated ordinary clay pots will burst apart eventually even at ground level. Up on a balcony there is no connection with the soil, making freezing up and damage of the pots--and the plants--even more of a problem. Rosemary varies in hardiness, but many forms are not fully hardy even in the ground. In pots, up in the air on a balcony freezing out will be all the more likely.
     
  7. KarinL

    KarinL Well-Known Member 10 Years

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    Yes, as Ron's and Rima's answers suggest, there are two questions here, the survival of the plants, and the survival of the pots.

    What breaks pots apart in Vancouver is the combination of wet plus cold, in the event that it freezes when the pots are saturated with water. They don't so much break as flake, in my experience. So the main thing that's going to protect them here (vs in the east) is drainage. Water needs to be able to drain out of the pot and away from the pot. Your balcony has an overhang, so you may have an advantage in this area anyway, as they won't get all the rain. It is certainly true that there are higher and lower quality pots, and this is true of both glazed and unglazed varieties. But I've had some cheap glazed pots, even some rated for indoor use that I leave out over winter, for several years. Terra cotta, I just don't think you can consider that a long term investment in Vancouver unless it's the highest quality and/or you keep it dry and frost-free over winter. If you enormously value the pots, you can empty them and put them in storage, and then plant them up again in spring.

    Now, your plants may survive even if the pots break or flake. That depends on the plants. As Ron says, it's colder up in the air, and it's also colder in a pot than it is in the ground - approximately one zone. I have lost plants that are hardy only to Zone 8 winters because they've been in pots, where it feels like Zone 7 (colder) to them. It might even feel like Zone 6 on a highrise balcony.

    Outdoor plants often like it cool in winter so bringing them in isn't always a great option.
     
    Last edited: Aug 12, 2006
  8. Ron B

    Ron B Paragon of Plants 10 Years

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    Roots are less hardy than tops, pots on a balcony have frost penetrating from all sides. In such situations any less-than-hyperhardy plants that are to be kept over from year to year need to have the containers protected from deep freezing.
     
  9. chuckrkc

    chuckrkc Active Member

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    As far as pot survival, what do you think of fiberglass pots? Some fairly well mimic concrete, as far as looks go. Also, let the pots dry out (if such can happen in Vancouver environs) and put a heavy duty plastic bag over the pots to keep moisture out. Maybe a board to keep the plastic from pooling water. That's a tactic in the Midwest. Keeping the moisture out is more important than just the cold.

    Interesting about the Japanese pots.
     
  10. torbie

    torbie Active Member

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    This doesn't bode well :/ The roots, the plants, the water, the freezing , the potential breakage... my poor plants! I'm on the second floor, not too high up, not sure if that makes any difference.

    I'm thinking of Rima's idea to put them into planters with mulch, keep them dry and cross my fingers! Just curious Rima, where are the places to find Japanese pots in Vancouver? I may consider repotting them into better pots if it isn't too expensive. I'll have to repot them in the spring into larger ones... if they make it!

    Thanks to all of you for your suggestions and information! Much appreciated.
     
  11. Rima

    Rima Active Member

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    Hi, I guess I was thinking in bonsai terms... J. pots vs C. pots vs others, and should have realized it may be difficult, or certainly exhorbitant to find and buy pots known to be Japanese from garden ctres (I just get mine from bonsai dealers - but the styles might not suit what you're doing either). However... mica (resin compound) pots are great, they look like earthenware (dk brown usually), are superstrong and not just 'cold' wise, are lighter than ceramic, and cheaper. I get mine from www.bonsaimonk.com and while they may be shallower than you're used to for growing things, they're also wider, and if you set your plants just off center in them, in a fast draining gritty mix (perlite, aquarium gravel, a little coarse soil (not peat) and possibly some bark mulch (pieces no larger than 1/8"... hard to find), tease out lower soil on existing rootball and gently open roots up laterally, they'll fit well, especially when you slightly mound the soil towards the middle of the pot. You'll want to water more often than you might have been, and feed more often (if not full strength) because water will drain quickly, but you'll end up with terrific plants ... eventually little trees (trim roots x 1/3 every 2 yrs) and won't have to worry about pots cracking. When foliage gets straggly cut it back hard and watch it get bushy - then you can prune minor branches (in spring) to streamline the trees. ALL that being said, you can just order deeper mica pots from that place (they're great to deal with) and just grow your plants as you have been, and forget the bonsai thing. However, it's still a good idea to mulch the pots into either larger ones, or boxes (with their own drain holes) for winter, not because the pots will crack, but to keep the plants from becoming too cold if they're not 100% hardy there.
     
  12. torbie

    torbie Active Member

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    Hi Rima, thanks again! For some reason I forgot you were back east when I asked if you knew of any Japanese pot places out here! I checked out that website. Some very nice bonsai pots there, and some regular ones as well. I think I know of a bonsai store on my bus route.

    Some day I'd like to get into bonsai, maybe sooner than I'd planned!
     

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