Seed Storage Techniques

[Tucson Grower]

For more than 3 decades I've been storing my saved seed in small glass vials in which I include a small quantity of calcium chloride desiccant, impregnated with some cobalt chloride as a colored (blue/pink) indicator. This arrangement seemed to work well. Later I switched to silica gel with orange/green indicator dye. It was a little less messy and a little cheaper.

In the past few years I've changed my technique a little more. I now put my seed in small paper envelopes, with their info written on them, then I place them in plastic bags with zip seals, after including a small quantity of active (orange) silica gel desiccant, I seal them. If the seed was not completely dry yet, the desiccant will quickly (in a few hours or days) turn green. It will then need to be replaced and watched again, repeat until desiccant remains orange. I like this desiccant, also, because with a defrost setting on a microwave and a paper plate, the trapped moisture can be removed and the desiccant will again turn orange and after cooling be ready to reuse.

Recently I've read that after drying, seed will often remain viable for extended periods, if kept at freezer temperatures. I plan to research this more, then possibly obtain a small freezer to test it out.

I do remember that, while I was in college, back in the late 1980's, I was shown a freezer that maintained temperatures near absolute zero. I believe the seed they kept there was desiccated of all moisture and the seed was submerged in, if I remember correctly – glycerin.

I plan to add to this thread as I continue to research modern seed storage techniques and practice them.

[heavyhitterokra]

Thanks, for starting this thread. I still have a lot to learn in this area. It ought to be very interesting as time goes on.

[macmex]

Oh my! How did I miss this thread until now!? This is SUCH an important and helpful topic! Thanks for starting it. I can't write much now but plan on coming back to contribute here. Tuscon, thanks for starting this!

[Jim Tjepkema]

I found a paper, I will have to look up this reference and send it later, which related relative humidity to seed moisture. If the relative humidity in a seed storage container is 40 % or lower and not below about 25 % the seed moisture will be low enough for long term storage. You can use Hydrion indicator paper which you can buy online to find out what the relative humidity is inside your seed storage container. This indicator paper is a little hard to use because it only gives a crude measure of humidity. It is good enough to tell you if the humidity is not close to where you want it. You can buy small humidity gauges that will fit in seed storage containers to get a more accurate measurement. I bought one from ThermoPro that works for me.

You have to be careful using silica gel to dry seeds or keep them dry because it can dry down seeds too far and damage them. Use only a small amount of silica gel or very little if the seeds are small. It would be good to put humidity indicator paper in the container where you are using silica gel to make sure the silica gel isn't drying down the seed to point where it might damage the seed.

[macmex]

I've been a little less refined that you folks. I just leave me seed out for a couple of weeks in room ambience and package it up in airtight bags or bottles for frozen storage. The individual packages go into bins which are then stashed in the freezer. I use bins primarily as a way of organizing.

When I'm processing seed we often have the AC running, which sucks humidity out of the air. In the fall, ambient humidity isn't high, as a rule, so we don't need the AC or any other means of drying the seed. So far this has worked pretty well. I do appreciate the more scientific approach, just haven't taken time to do it myself.

[Jim Tjepkema]

In my house the humidity is low in late fall and in the winter. To keep my seeds from picking up moisture when the humidity is higher I seal them in canning jars by tightly screwing down the lid. If you have the Hydrion humidity test strips available, that are fairly cheap and available online, you can put a part of a strip inside the sealed jar to monitor the humidity in the jar. You can tell if the seeds were completely dry to a good level when you sealed them in the jar by looking at the color of the test strip. Also when you take seeds out of the jar to plant and put any seeds you didn't plant back in the jar you can tell if they picked up moisture when you did this. I think places that sell seed saving supplies should have Hydrion test strips available for purchase by seed savers.