Seed Keeping Question

How do you keep your seeds? In the refridgerator? Outdoors? Just curious in the ways they are kept and which are best for short term (for the present year) and long term (for the next year).

I keep mine indoors in a closet...but humidity is kept below 40% at all times due to DH's vintage guitar collection. Room temprature, dark, and low humidity are all most seeds require to stay viable. Freezers and fridges are ok too...and lots of folks use them , but be careful that moisture does not collect on the containers...that happens more often than not....the backage isn't moisture proof...or it's not allowed to come to room tems before opening. (this will cause the container to sweat)

Thanks melody!! That's good info!!

(bump)

The most important thing is to get the seeds as dry as possible before going into storage. In some climates, air-drying won't get seeds much drier than 50% RH (relative humidity, or "relative humidity equivalent"). That's OK for a year or two, but 15% RH gives you viable seeds for 4 times as many years.

Seed life span approximately doubles for every 10% reduction in seed eRH.

http://www.kew.org/sites/default/files/4_ppcont_014345_Post-harvest%20handling%20of%20seed%20collections.pdf

http://www.kew.org/science-conservation/research-data/resources/millennium-seed-bank-resources

"Drier" means "more dormant". They consume less stored food that way, and they release less humidity since their metabolic rate is much less.

If you store seeds in paper envelopes, humidity can pass very freely right through the paper. Exposed to room air, the seeds' humidity goes up and down with the weather, including on rainy days.

You could seal air-dry seeds in paper.
Then seal some desiccant like silica gel in paper.
Then put both inside a glass jar or plastic jug and seal the jar tightly.

That will dry the seeds thoroughly, for long term storage (many years in many cases).

You want some humidity indicator like a "humidity card" in the jar, to be sure the desiccant hasn't been used up, and also that you don't dry the seeds below 15% RH.

Drierite relative humidity cards at 40 cents each:
https://secure.drierite.com/catalog3/page15b.cfm

ULINE humidity cards, $18 / 100 cards
http://www.uline.com/BL_1002/Humidity-Indicator
http://www.uline.com/Product/Detail/S-8028/Damage-Indicators/10-60-Humidity-Indicators

You can also bake dry rice to produce a gentle desiccant (but don't over-bake it: even light brown means that it's a little scorched, and that reduces its water-absorbing capacity.

Other desiccants are:
powdered milk (very gentle or weak)
Oil Dry (oil-absorbent Bentonite clay containing Montmorillonite) - auto supply stores
and Drierite - anhydrous Calcium Sulfate (very strong)
https://secure.drierite.com/catalog3/page4a.cfm
https://secure.drierite.com/catalog3/page4b.cfm





Many people worry about sealing seeds in plastic, since any seed that's still alive releases SOME humidity as it metabolizes. That might apply to triple-sealing seeds in foil-coated Mylar, yet a few companies and many seed banks do just that safely.

Zip-Loc baggies leak humidity and oxygen through the zipper, and even right through the polyethylene plastic sides! So as long as you get the seeds really dry and dormant before putting them into Zip-locs, it isn't a major concern for the first 3-5 years of storage.

My longest stored seed were left remaining in the pod and hung in a open bag .
Most I keep in a empty Baby Wipes box in the fridge crisper ,,
I like the dry hanging better , except,, unless you get radishes and beans really dry , they sprout in the pods ..

>> in the fridge crisper

Actually, that is the most humid part of the fridge, not the driest.

It is the only part of the fridge I am allowed ,(you get it) lol

I understand!

If they are sealed up really tight, outside humidity shouldn't matter.

But you have forgotten the other main determinant of viability in storage... temperature.
The person from the seed bank at Kew told me that storage viability doubles for every 10 °C of reduction in temperature.
Hence Temperature of fridge ~4°C; temperature of freezer ~ -16°C thus 20°C difference and fourfold better viability of properly dried seeds if stored in the freezer.
Second thing: humidity in freezers is less due to the shedding of water vapour as ice crystals.

I agree that seeds stay viable longer if stored closer to 4°C than to room temperature. I didn't realize that "storage viability doubles for every 10 °C of reduction in temperature". And it makes sense to me that deep-frozen very dry seeds would last longer than room temp very dry seeds, since nothing slows metabolism like being frozen hard. Serious seed preservation banks use freezing temperatures, or maybe cryogenic temperatures.

>> Second thing: humidity in freezers is less due to the shedding of water vapour as ice crystals

Certainly absolute humidity (grams of water per cubic meter) is less at -16°C than in a warm room. Even if the RH were 100% in a freezer, only a very small amount would be in the vapor state at 3°F.

However, usually it is Relative Humidity that matters to seeds. (I don't know for sure that is true once they are completely frozen). The RH in a freezer depends on a lot of things, mainly whether it is a "frost-free" freezer, and how often the freezer door is opened.

I guess most modern freezers are "frost free". Some mechanism is built in to suck out the 100+++% humidity that blows in and condenses every time the door opens. If it were not for the "frost free feature", the RH in the freezer would rise to 100% right away and stay there because the freezer surfaces would be covered with a little frost, or a lot of frost, or layers of ice.packs of seeds would be covered in frost and ice after the freezer door had been opened just a few times.

The "frost free feature" acts like a bottomless bag of desiccant and keeps condensed humidity from building up into layers of ice. In fact, it will dehydrate the surface of poorly wrapped packages in the freezer, causing "freezer burn". I think the "frost free feature" probably keeps the humidity below 20% once it evaporates condensed water (frost).

I guess modern freezers would prevent frost build-up, but if I stored seeds in a freezer, I would double-bag them with two gallon-size freezer bags, and keep a desiccant pkt between the big freezer bags. Then humidity could condense and freeze on the outer bag as much as it wanted to, but even if humidity diffused through, the desiccant would catch it before it could diffuse into the inner bag.