safe cold storage for bulbs and seed pots

[Gene Mirro]

In addition to the garden, I have three areas where my plants "chill out" over winter.  One is my little greenhouse attached to the house, which I try to keep above freezing.  I usually have a fluorescent fixture and sometimes a halide "marijuana" light going out there from fall into midwinter, since I have found that many seedlings of alpines and wildflowers, including lilies, love to grow and have minimal losses in very cool conditions.  Meconopsis, Gentians, Calceolarias, Lewisias all thrive.  When they get a couple of leaves on them, I bring them into my unheated (50 - 60F) basement and grow them under lights for the rest of the winter.  With this tremendous head start, most perennials will bloom the first year from seed.  The additional energy cost for the basement fluorescents is minimal, since all the heat that they make goes directly towards heating the house. 

My secret weapon for chilling seed pots and dormant bulbs is my nursery fridge, a Sears 60721, which regulates at 40F or so.  But the amazing thing about this unit is that it can both cool and heat in order to hold its temperature.  This means that it can be placed in an unheated garage or shed where the temperature can go as low as 10F (-12C), and it will maintain 40F inside.  So this is a natural place to chill plants that I don't want to take any risks with at all.  For bulb storage, I pot them up in slightly moist potting mix, and place the pot in a large plastic freezer bag, and then into the fridge.  Anything not bagged will dry out.  In summer, I also use this fridge to chill seed pots which I am growing on an "inverted season" schedule; that is, they are stratifying during the summer, and growing under lights during fall and winter.  It's perfect for the Norman Deno "12 weeks warm, 12 weeks cold, repeat" germination technique.  It's one of the best gardening investments I've ever made.  (For you cynics out there, I don't work for Sears, nor do I own Sears stock.)  Everything in this fridge needs careful watching, since it is completely dark inside, and seedlings will become elongated and weak if not promptly removed after sprouting.

Image 003 shows my lilies, etc. growing under lights in the basement.  Epilobium rigidum, a beautiful little alpine from northern California, is on the right.  I use sheets of insulating plastic foam as light reflectors all around the growing area. 

Image 001 shows my fridge, loaded almost to capacity with goodies and treasures for next year's garden.  And I have included a picture of Epilobium rigidum growing in its native habitat. 

[canyoncreekman]

Gene,

Thanks for sharing these specific gems of 'hands on' experience. The photos really clarify and add to the methodology.

 Also pleased that you are experimenting with epilobiums. Up here in the Canadian Rockies they are one of the many genera that haven't yet been studied in detail and their taxonomy not clarified. There are at least 3 or 4 small unstudied species waiting for a botanist to give them a name .  I still come across an epilobium at sub alpine or just into the alpine ecosystems and it takes a while to figure out it's one of this genus.  They are relatively east to grow in our dry zone 3 alpine beds either from seed or a bit of rhizome.

I like your comment on the refrigerator's function as not only a 'cooler' but a 'warmer'. Also, I agree with your observation that dessication in the fridge needs to be guarded against.  Our native species lilies, however (L. philadelphicum and L. columbianum) only dessicate in cool conditions (like a fridge) and not freezing. If we put them in the freezer department it shuts them down completely and they come back strong when the growing season rolls along.
         

[Gene Mirro]

Nelson, I was surprised by your comment about the freezer.  My understanding is that any moist live tissue that goes into a freezer at 0 degrees F becomes dead tissue, because the freezing water bursts the cell walls.  Is that not correct?

[canyoncreekman]

Nelson, I was surprised by your comment about the freezer.  My understanding is that any moist live tissue that goes into a freezer at 0 degrees F becomes dead tissue, because the freezing water bursts the cell walls.  Is that not correct?

Gene,

 Last week our temperatures were above 10c and since then we've had a cold snap and it's minus 20c.  Much, much colder than any freezer. We have hundreds of varieties of plants that survive and do fine. Bulbs like those of Egyptian walking onions, etc. sit on the surface all winter and will burst to life quite happily next Spring.  Iris rhizomes sit on the surface and will put on a display in late spring. We even have calypso orchid bulbs sprouting on top of the compost pile after being frozen solid for 5 months.

 Many  plants, especially those at higher altitudes, undergo a freeze-thaw cycle during the growing season. Temperatures in the alpine zone can be plus 25c in the day and well below freezing at night.   In winter months the frost depth (frozen ground) can be a couple feet down over much of the expanse of Canada, Russia, and so on.  Frozen ground is not the exception in the evolution of terrestrial plants in the world but involves a good chunk of the world's land mass.   Here in Alberta our tulips, crocus, lilies and so on are in rock solid frozen ground, much colder than a freezer, until spring.

 I would think that the difficuly of growing many alpines in more moderate climates isn't freezing but near freezing temperatures that fluctuate upwards now and then and plants break dormancy.  Here we get warm mountain Chinook winds in winter that raise the temperatures in the mid teens celsius but the ground remains frozen and keeps the plants in a deep freeze.

 Of course there are lots of perennial plants we use as annuals because the cells do burst if frozen. Our house is a flurry of activity when the first hard frosts come and we have to rearrange our furniture to accomodate the 'wimpy' plants.     

 We even have wood frogs one can put in the freezer for a week, take them out... they then thaw out and hop away.  Not that one wants frogs in the freezer.   

[Gene Mirro]

Your post reminded me of my years in Pennsylvania, where our winters were very cold (but nothing like yours).  I remember what you were talking about:  iris rhizomes that seemed completely invulnerable to the cold.  I also know from experience that many hardy plants will die if planted in containers and frozen quickly (overnight, for example) or thawed quickly.  So I keep trying to understand the fine points that make the difference between life and death.  This is my favorite theory:  plants in the ground will not die even if frozen, since the rate of freezing and thawing is much slower than in pots.  I believe this is the problem with the freezer:  if you take a bulb that's at 55F and put it in the freezer at 0F, it is frozen solid in a couple of hours.  When you take it out, it defrosts in an hour or two.  This is much too fast, and the bulb has turned to mush.  If the bulb is in a large container full of moist soil, its chances of surviving the freezing process are much improved, since it takes a long time to freeze.  I once owned a small plant nursery, and had roughly 3,000 pots out in the open (but covered with straw) on a night when it went from 50F to 8F, and then back to 40F a couple of days later.  I lost all but about 25 plants.  I remember that Lilium canadense and Gentiana septemfida and asclepiadea survived, but my other lilies, tulips, narcissus, perennials all died.  Also, in western Oregon, our winters are mild and wet, so the plants don't acclimate to cold conditions.  Some plants don't even stop growing.  That could be another big factor.  Fascinating subject.