Bulbs Can’t Freeze

Freezing seem like as good enough topic as anything because that’s all we seem to have in the forecast.  This is like the third week of real winter temperatures and after a bunch of warm years it seems so…. endless.  Realistically three or four months of winter wouldn’t be anything surprising in this zone, so with two more months to go there is no reason to complain.  It’s just the warmer years of late had me kind of enjoying witch hazel in January and snowdrops throughout.  Toughen up I say!  Truthfully I should be grateful for the nice solid cold, and the way it freezes up the soil and tells the bulbs to hold on, don’t be fooled, February and March will be early enough to start your growing plans.

frozen colchicum bulb

Colchicum x byzantinum bulbs are big, and my soil is shallow, and often they just push themselves up and practically sit on top of the soil.  Obviously in this position and with temperatures down to 0F (-18C) the bulb and new growth will freeze

Some of the top spring disasters (off a quite lengthy list) have been the result of warm winters which bring things up way before their time.  Hellebores in particular must be an unusually optimistic plant which falls for this fake spring followed by a hard freeze every time, but snowdrops can be fooled as well.  Often I’m surprised by how well tender growth can survive brutal freezes but it’s not always a happy ending.  Right now a better gardener would be covering some of these goodies to keep the worst of the weather off of them.

snowdrops in the snow

We will see how well ‘Godfrey Owen’ tolerates the rest of winter after having already come nearly into bloom.  Tonight will be cold, next week looks colder.

I guess that brings me around to the title of this post.  I often see claims that hardy bulbs need to be protected from freezing, especially those in pots.  I disagree.  I used to pot up bulbs and throw them into an unheated shed where they would freeze solid for months without ill effect.  I’ve dropped bulbs in the fall and had them root into the surface, survive winter exposed and also do just fine.  There’s more to it of course but without exposing my own ignorance I’ll just point out a few ‘excepts’ which I’ve come across.  Bulbs need to begin rooting before they freeze.  Potted bulbs should be on the dry side before freezing.  Exposed pots which freeze and thaw repeatedly will suffer.  -and the one which I can’t figure out is that potted bulbs will rot when snow melts and then re-freezes on the surface of a pot of bulbs, especially later in the year.  My balcony gardening year was always off to a tragic start when a big pot full of tulip and crocus sprouts would all just stop growing after a cold spell hit with snow or rain freezing on top of the pot.  Weeks later I would finally give up and pull the still green and solid sprouts out, leaving a rotted bulb behind. 😦

Well that ended on a sad note.  If anyone has some thoughts on this let me know.  I find the easiest way around this is to just cover planted pots with autumn leaves and then uncover them as soon as temperatures warm, but you know how greedy I am with my autumn leaves!  Maybe a board on top to keep the snow and rain off would be good enough, I just have to remember to try that (again) and make a note of how it works out.

In the meantime stay warm and consider that (here at least) the daylength is getting longer by about two minutes each day and we’ve added about 30 minutes since the shortest day of the year.  I’m sure we’ll be in flip flops before you know it 😉

23 comments on “Bulbs Can’t Freeze

  1. Brian Ellis says:

    “I can’t figure out is that potted bulbs will rot when snow melts and then re-freezes on the surface of a pot of bulbs” – I think this is when botrytis can happen. The other thing is that when pots freeze and the soil is wet the roots can be damaged, and as they are simple roots (ie that’s the only ones for that particular year) they can’t feed the bulb…I think that’s right!

    • bittster says:

      I’ve noticed that many better gardeners bury heating cables below potted bulbs which may freeze, and that seems to work quite well, so just protecting the roots alone seems to point towards damage below ground being the issue. Wet also seems to be a problem. Plants which die in the open garden sometimes survive in pots if I place them in a spot which receives little snow or rain, even if that spot is up on the deck exposed to wind and the full brunt of winter.
      -and thanks for the comment. I’m both excited a snowdrop expert has admitted looking at my blog while at the same time slightly embarrassed for all the nonsense you’ve surely come across!

  2. Paddy Tobin says:

    When I read of conditions where you have -18C I realise that you are speaking of circumstances far beyond my experience in south-east Ireland. The lowest temperature we have had in our garden was -7C in the winter of 2010/11 – all the dahlias in the ground were killed along with many cannas. We never experience conditions of cold which would threaten our snowdrops. As Brian said above, it is the alternating of freeze and thaw with wet conditions which is more of a problem as it leads to botrytis.

    • I am further north than Sorta, and we had -23C earlier this month. My nephew, who is going to college near the Quebec border, had -33C last night.

    • bittster says:

      Heh heh. I saw your kniphofia in bloom recently and imagined the blackened corpse of a plant if it tried that here. I’m not a fan of grey skies and muddy lawns, but snowdrops for months throughout the winter does have its attraction. Also having blooms which last and last rather than a week or three of frenzied blooms between freezer and furnace is also a nice consideration. We’ve had seasons where I’ve sat on the lawn admiring snowdrop blooms in short-sleeves and a 70ish F (~22C) breeze blowing. Kind of nice I thought, but I suspect you might begin to melt 😉
      I might need to experiment a bit again with a few bulbs in pots next winter. Nothing valuable like a snowdrop, but maybe a couple dozen tulips to start. In reading your and Brian’s comments I think I should really focus on the moisture levels and see if something comes of that.

      • Paddy Tobin says:

        I think the close down of gardening in winter would be so very hard to deal with. Although our conditions can be uncomfortable in winter, at least we can get out there and potter about and, yes, the snowdrops are a great winter interest.

  3. Eliza Waters says:

    I agree that we’ve been lulled by a few mild winters. Even this one so far isn’t as cold as it was a decade or so back. Remember when we’d get a whole week that hovered in the teens and single digits? For the maples I lovingly planted 30 years ago, I welcome the super cold weather… they need it. However, the yo-yo-ing weather isn’t good at all. Poor plants!
    I don’t dare put a pot of bulbs out in our climate. Anything ceramic would surely freeze and crack. Faux might work, but still. I cover my hellebores (in the ground) with evergreens and oak leaves (which don’t mat down) and remove them in March to avoid them coming up too early. Even at that time, if it dips into the low 20s/teens, I put buckets over them until it warms again. Nothing so sad as having the annual show a bust!
    Stay warm this week!

    • bittster says:

      Now I feel guilty. I was thinking of pulling out a few buckets, but got distracted by all the rabbit tracks in the snow and hastily dragged some more fencing out for a few undefended plantings. Once that was done I decided it was too cold for second guessing hardiness.
      This cold January should set the bulbs and the gardener up for a relatively stress-free February. As long as there’s a little snow I’m quite sure the bulk of them will be fine, and all we have to do then is hope the yo-yos stay away!
      I miss having fluffy oak mulch. The maples break down so nice and fast, but like you said the oak is so much nicer for a mulch which doesn’t mat.

  4. A couple of years ago I went to Cornell as part of a GardenComm meeting. We heard Professor Bill Miller, head of the Flower Bulb Research Program, speak, and one of the things he said was that he had observed the occasional daffodil bulb that had been left on the soil surface all winter bloom in the spring as if nothing had happened. So there’s your expert witness. I have seen it myself, in daffodils, snowdrops, and colchicums. Of course, any tulip bulb left on the ground would get eaten. And I have had the same trouble with tulips in containers. I guess one solution would be to drag them under cover every night until the container is no longer in danger of freezing. I’ve pretty much given up trying to grow tulips. Between the rodents and the wrong kind of soil (NOT free-draining) it’s never gone well. Which is a pity, because they bloom at just the right time, between the daffodils and the alliums/camassias.

    • bittster says:

      With an expert witness in place I’m going to have to play around a little more with potted bulbs and see what I can manage. Digging them into the compost pile or dumping some leaves on top isn’t the hardest thing to do, but if I can just skip a watering and throw them in a sheltered spot so much the better!
      It would be a sad day when I have to give up tulips. Oddly enough my soil is also not well-draining, but it does dry out in the summer and then resists soaking up any rain showers once the heavier rains hit. I sometimes imagine my soil being similar to their native haunts, and that’s probably not a good thing.
      Deer are my biggest fear. The rabbits don’t seem interested in tulips when there are crocus and dandelions to eat, but even one deer in the garden leaves its mark.

  5. Chloris says:

    I’m glad we don’t have this problem. My snowdrops and hellebores are in bloom. If we get any snow and cold weather, they will look a bit droopy for a bit but then they perk up when it gets a bit warmer.

    • bittster says:

      I’m also glad you don’t have this problem. The pictures of your winter garden and the snowdrops appearing in February tide me over until the thermometer begins to rise again.

  6. pbmgarden says:

    I hope ‘Godfrey Owen’ takes a liking to the cold weather and suffers no harm. Even in North Carolina we are forecast snow tonight again. Flips flops are ready though…

  7. Pamela Hubbard says:

    We were spoiled the last several years, lulled into forgetting how brutal a Pennsylvania winter can be. I planted tulip bulbs in my cutting garden for the first time for many years–keeping my fingers crosses that they will survive the temperature fluctuations and the rodents. Hoping the calla bulbs that I have in a pot in the basement survive too. Wishing ‘Godfrey Owen’ all the best. P.x

    • bittster says:

      I haven’t yet admitted how much of the vegetable garden has been planted with tulips. They’re not as big and perfect as the ones you had this spring, but I know they’ll be colorful and just as welcome. Hopefully this summer I can resist the compulsion to dig and save them all for replanting!
      Oh if I think back to the massive piles of snow lining the road, and the ski resorts which didn’t even need man made snow…

  8. Lisa at Greenbow says:

    I have found these freezes and thaws of winter are truely difficult to understand when looking at potted plants outside. I agree that dryness does help. I have several plants in pots under the eaves. They may get a little moisture but not much.
    Your nonsense is one of the main reasons why I read your blog. Such a fun yet serious look at the garden. I even learn a thing or two here on occasion.
    Cheers and warm thoughts for the coming growing year.

    • bittster says:

      I shall continue to dispense nonsense with every post 😉
      Last winter a pot of ornamental grass was pushed up under the eaves for the winter mostly to save the pot, but shockingly the grass survived as well. Planted in the soil it always dies, but dry and in a too-small pot on the exposed deck it lives. Weird!

  9. Cathy says:

    Some interesting thoughts. Firstly, my hellebores only seem to suffer if we have long dry freezes or extremely hard frosts with no snow cover. Otherwise regular frosts are no problem for them at all. But mild winters do encourage them to produce flowers earlier. And I plant bulbs in plastic pots and like Lisa they stand under the eaves from the end of November onwards, covered with woodchips, and I water very sparsely if not too cold. The plastic pots go into prettier terracotta ones in spring. Hope it isn’t a damaging freeze you get this week and is over quickly!

    • bittster says:

      I will have to try more things potted up and under the eaves. I love being able to move pots full of bulbs around, but getting them through to the spring bloom is always more work when you’re spending so much effort getting them through the winter.
      There should be a few spare tulip bulbs next fall, I’ll need to experiment and keep track of it all.

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