Freezer Questions

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Kathleen Plunke...
Freezer Questions

As part of our desire to keep a low energy footprint, we've lived for many years without a freezer, but lately I've been thinking of getting one, mostly for seed storage.  It would let me make use of a larger percent of the seed I get from high-population crops before it loses germination, and let me space generations farther apart  and thus grow more varieties (see  inbreeding topic).

I'm trying to understand the relationship between 2 pieces of advice I've heard:

1. Any freezer or fridge made before (???date) will be extremely inefficient and is not worth using due to the cost of electricity compared to buying a new energy-effieient one.  

2. Fridges and freezers made after (??another--or the same??? date)  will not run correctly if they are kept in a garage or outbilding because they changed lubricants in the motor and it will not run when it is cold (but still warmer than you want your food/ seeds to be).

It would seem to make sense to keep the freezer in an unheated space rather than using energy ( cutting wood) to heat the house and then more energy to cool the freezer, but it sounds like that might not be possible. . .???  

Anyone out there know the relevant years for this and whether they are related?  And whether there was a window of efficient freezers that could still be kept in an unheated area?

Or understand refrigeration physics well enough to explain it to me?

What is your experience using freezer storage for seeds?  


Jim Tjepkema
reezer Question Answer

I think it might be good to get the latest highly efficent freezer and keep it inside.  With high effiecentcy it might use less energy than an inefficent one placed outside.  An efficent freezer used inside might maintain about the same tempersture all year long which would be good for seed storeage.  An inefficent freezer or any freezer sitting out side might have some flutuation in temperasture during very cold weather when it might get extra cold.  Flucations in temperature during storeage might shorten the life of seeds in storesge.   That's my thoughts on this topic.  I am not sure that what I have said is correct.  


Melissa Hilsgen
Melissa Hilsgen's picture
Hi Kathleen, we put all our

Hi Kathleen, we put all our (new) chest freezers out in the shed...and put a thermometer in each one, and they are staying evenly frozen year-round. In addition to seeds, they have our meat and veggies in there as well, so I keep a close eye. I have 6 small 7Cu FT freezers, they offer more flexibility than a couple of larger ones. they are less then 3 years old, and run on practically nothing all year. Even in the summer, as the building is cinder block and cement floored and under some trees, so it stays relatively cool. 

I think Jim is correct, at

I think Jim is correct, at least about the fluctuation in temperature, however i'm not sure whether a DOWNWARDS fluctuation is necessarily harmful. I know that we have an old chest freezer and a much newer upright one in an outbuilding where it is exposed to temps as low as -20+degrees and high winds, yet we have never had problems with them, although they're on all the time (of course not running when it's freezing), and we go into them almost daily.

I need to resolve this question for myself, as i'm planning to invest in a series of high-efficiency freezer for my new seed office, which is heated sporadically. Since freezing can easily triple the viable life of seeds, it would be a huge cost-efficiency to not have to regenerate samples so often.

12540dumont's picture

In central coastal California, we can keep our freezer in the barn.  In Northern California, a freezer in the garage does not work in the winter.   Why?  Because it's colder outside than in the freezer.  Which causes the freezer not to cycle on.

Testing again


Steve Wood
Steve Wood's picture
Thanks for this discussion

My thanks to Kathleen for starting this thread and to all who have contributed to it.

We have a medium sized chest style, manual defrost freezer we bought 15-20 years ago. It's always been in our unheated, but insulated garage and runs well. But at it's age, it could fail at any time.

This forum thread has given me some good food for thought if (and when) our old freezer fails. Hmm, maybe I'll want to get it repaired at that point.

Freezer Question

Hi Kathleen, not to add too much confusion to the conversation, but I'm under the impression that storing seeds in a freezer is only advisable if you plan to leave them there for a longer period of time, say two to five years, undisturbed. If you are storing seeds in a freezer, there is a greater risk of condensation forming inside the packet once you remove it—especially if you've packed the seeds in ziplocs—because of the temperature differential between the freezer and room temp. If you need to remove seeds from the freezer, best to put them in the fridge for a while first, then bring them out to room temp, then wait a while before opening the packet. I store all my seed stock in small, so-called bar fridges in the unheated basement. These actually use an amazingly small amount of electricity. Back-up seed is in a very cold root cellar. I pack seeds in ziplocs because I have quite frequent power outages and if I don't catch it in time and the little fridges self-defrost and the seeds are in paper packets, I'm in deep trouble!

Melissa Hilsgen
Melissa Hilsgen's picture

I am of the understanding that Ziplocks are not actually airtight and are therefore unsuitable for freezing? Although seemingly waterproof, anyone who has frozen liquid food in them knows they leak, and are easily damaged in the freezer. This could lead to moisture fluctuation for the seeds. Heat-seal mylar bags are completely airtight. 


Hi Melissa,

Yes, ziplocs are not airtight or completely waterproof, even the so-called "freezer" versions, but they protect my seeds adequately in the small fridges. Heat-seal is a good idea for long-term storage.

Wow, this thread gets more

Wow, this thread gets more exciting as it goes along. So, Sylvia, if i understand you correctly, you're saying that while ziplocs are not the end-all, they are a huge improvemeny on ambient, which certainly makes sense to me?

I had thought it was taken for granted that everyone realizes you have to pre-warm seeds out of the freezer before opening them, due to the condensation S describes. It only takes a very few minutes, but is absolutely essential. Therefore an additional strategy is to pre-package seeds into several smaller sample-sizes within a larger bulk-pack ziploc, so one can remove only what's needed now from the freezer. Plus the double-packet gives extra protection. Btw, i'm under the impression that the permeability of zip-locs is almost entirely thru the seal, not thru the wall itself. I do know that others have had very good results from just taping over the seal, however i'm not sure how that compares with heat-sealing. I believe the laminated plastic-foil packets which SSE uses are supposed to be best of all, but they're pricier and of course have to be re-heat-sealed after every removal.

Thanks to Kathy for kicking this one off.

Jim Tjepkema
I find the very tightly

I find the very tightly sealing plastic vials that can  be purchased from Southern Exposure Seed Exchange to be ideal for storing seeds.  They were tested and found to be completely air tight.  They are used commercially for collecting samples for testing in labs and other places.  I have some that I got free from a lab that was discarding them.  You can get small ones for tiny seeds and larger ones for big seeds from SESE.  They are strong containers with the lids attached by a strap and can be used over and over again for many years.  Also, bags of seeds can be packed in canning jars with the lids screwed on tightly to keep them dry.  I wouldn't do any long term storage of seeds in plastic bags because I think that plastic bags, the bags themselves as well as the seals, are not completely water and air tight.  I think moisture can migrate through plastic and could increase the moisture content of seeds decreasing their storeage life.  I dry my seeds with silica jell before sealing them in the air tight vials.

Jim Tjepkema
 I store most of my seeds in

 I store most of my seeds in a small student sized refridgerator.  To check on the temperature in this fridge I bought an indoor/outdoor thremometer and put the sensor for measuring outdoor temperature inside the fridge.  That allows me to check the temperature in the fridge quickly without opening the door of the fridge.  The wire from the outdoor sensor inside the fridge leads to the device sitting along side the fridge which displays the temperature inside the fridge.

Russell Crow
Freezer Stored Seeds.

When I remove seed from a freezer it takes more than a few minutes before I open the container. I allow them to warm at room temperature for a number of hours. Sometimes up to six hours depending on how large amount of seed is stored. I have also been told that frost free freezers are not the best to store seed in as the temperture fluctuates often when the freezer is trying to defrost itself which it does fairly often.