Seed Storage

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Title: Guest
Joined: 2010-12-23
Seed Storage

As I receive or harvest seed I store it in my freezer until I sow or distribute it. A good deal of my experience has been with rhododendron seed that I find retains viability for a very long time: perhaps 5 or 6 years ... I find freezer storage is "dry" and I use no dessicator. Are there any comments on shelf life of "alpine" seed in general?? E.g., what expectations should I have re: say, Townsendia ... or Eriogonum ... or is this just too general an issue (putting aside the issue of "ephemeral" seed). Some comments?

Lori S.
Title: Moderator
Joined: 2009-10-27

Interesting topic, Moyles!  So glad you have joined us!

Well, I have to admit that I don't take any extra care in storing seed.  Once it is thoroughly dry, I just pack it away in glassine envelopes and put it away until I need it again in the next planting season.  The humidity tends to be very low here (both indoors and out) so moisture problems don't tend to occur (in my experience, at least).

Last year, I ordered seeds of various alpine species from the Czech seed collectors (Pavelka, Holubec).  Where the seed collection year was noted, quite a bit of it was from 2006 and 2007, and some was even older than that, e.g.:
Campanula kirpicznikovii - seed from 2004
Dracocephalum foetidum - seed from 2003
I was pleased with the germination rates overall.  (I'm afraid I don't keep such good records as to be able to record percentages of germination (as I'm too lazy to count seeds), only whether it was nil, sparse, generally good or "yikes, I'm really gonna have to thin these out!")

Calgary, Alberta, Canada - Zone 3
-30 C to +30 C (rarely!); elevation ~1130m; annual precipitation ~40 cm

Title: Guest
Joined: 2010-09-04

I collected seed of some amazing pure white Aquilegia caerulea in 1999.  I forgot about them and found them 10 years later in the garage.  According to Dr. Deno, seed of this age should have given 0% germination.  "Why not just broadcast them in an empty pot?"  Germination?  Wow!  Yes!  They'll flower this year and I can't wait to see the size of the flowers and their color.  I hope they maintain the beautiful bright white. 

The seed collection was done at 11,500 ft. elevation in full sun.  This gets me wondering if the frigid temperatures at that elevation gives the seeds a genetic "edge" to prolong their germination life.

There are so many variables in plants, seeds and their environments!  That's what makes growing by seed so fun!


Margin of the Great Basin Desert & Wasatch Mountains
4350' (1326m) Elevation; Zone 5a - 7a; 5 miles from the
climate moderating effects of The Great Salt Lake, Utah
J. Mikkelsen

Hoy's picture
Title: Member
Joined: 2009-12-15

Many seeds can live for years - hundred of years - if properly stored. If you remove pavements in a city lot of seedlings appear from seeds which have lain under the pavements for years. All kinds of topsoil have a seedbank, and some of the seeds live very long, but 10-20 years is common.

Rogaland, Norway - with cool, often rainy summers  (29C max) and mild, often rainy winters (180 cm/year)!

Title: Member
Joined: 2009-12-04

I do not store seed cold but I have read that they must be dry before storage and sealed in an air tight moisture proof container to prevent the formation of ice crystals which can rupture the embryo cells degrading germination.

From the High Desert Steppe
of the Great Basin and the Eastern
Escarpment of the Sierra Nevada Range
Located in Reno/Sparks,NV  zone 6-7
John P Weiser

Title: Guest
Joined: 2010-12-23

Thanks  for the refs!  Ultra detailed ... am reading them ... my general observation is that most seed I have handled is dry .... rh seed dries almost immediately from the capsule ... or dry enough.  Storing over silica gel in a glassine envelope is the safe way (or pollen in a gel cap). Have never observed ice crystals forming ... the freezer is dry cold. A tight container is certainly preferable.  Hard for the amateur to evaluate effects of storage ... was the seed viable, etc. before storage?  I think we end up depending upon (even casual) observations and postings to Forums such as this one.  Egyptian tombs aside!

Bill Moyles
Oakland, California

Title: Moderator
Joined: 2009-09-21

Most of my seed end up being kept at about 60F in the lower level of my house.  Some species that are known to deep freeze well, like Lilium spp., might be kept in the freezer if I am keeping them long term.  But if you do this with a self defrosting freezer, make sure the seeds are in some kind of insulated package.  The possibility of continuous freeze/thaw cycles can't be good. 

Rick Rodich    zone 4a.    Annual precipitation ~24 inches
near Minneapolis, Minnesota, USA

Gene Mirro
Title: Guest
Joined: 2010-02-25

Dry seed storage in the freezer is very effective.  Most seeds remain viable for decades.  Attached is an article that I wrote for NALS many years ago.

I just sowed my last batch of these about two years ago:

SW Washington state, 600 ft. altitude

Mark McD
Title: Moderator
Joined: 2009-12-14

Gene, thanks for sharing the seed storage tips, very interesting and useful.

Regarding your swiss chard for 39 cents, you certainly got your money's worth out of that one ;D

Mark McDonough
Massachusetts, USA, near the New Hampshire border USDA Zone 5
antennaria at

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