How to store seeds

I don't know why, but the topic of seed storage interests me. So I've been doing a fair amount of research and thought I'd attempt to write down here what all this new found knowledge means to me. It is really pretty simple when it's all boiled down but I am going to indulge the geek within me with a bit of seed storage minutuae for a while. Jump along for the ride if you like.

If you don't want to read any further then I'll just say up front I am convinced the best, most practical *orthodox seed storage method is airtight, low humidity, at O degrees F. A ziploc bag is NOT airtight. Seeds in a ziploc bag inside a mason jar is an excellent storage method though for the average person who isn't interested in storage for longer than 2-3 years. Heck if the global seed vault scientists are storing seeds in Northern Norway in a very deep freeze, then I think I should too.

How To Store Seeds
The goal of storing your seeds is to maximize viability. Viability is scientifically defined as having a 50% or higher germination rate. Obviously, we would like to be as close to 100% as possible.

Orthodox seeds are seeds that behave in a predictable manner while dormant. Avocados and most oak trees for example are not predictable seeds and are called recalcitrant seeds.

A bit about my research: I read science journal articles, research papers, marijuana growing books and tons of web sites and learned about how seeds behave under certain conditions. Some of it made common sense but some seemed counter-intuitive until I considered how temperature, humidity, condensation, light, oxygen, and the inevitable FLUCTUATIONS that occur under normal HOUSEHOLD storage conditions all factor together to optimize the seed dormancy and why. Basically a seed needs for storage the opposite of what they need for germination (oxygen, heat, moisture and light).

Why store seeds under optimum conditions? What's the big frggin' deal anyway? I've heard lots of people say, "well, I keep them in a drawer in my desk and they sprout fine." Maybe so but hopefully I can change your mind here. For me, every seed is expensive and therefore I want to safeguard them as best I can.

Another thing to think about is you should plan for long term but hope for the best. You never know what future holds so why not store your precious seeds well? It doesn't hurt and is easy to do. Would you rather regret that you ended up with stale seeds because you didn't get around to planting them when you thought you would?

If you're the type who never stores seeds for longer than a year, you can certainly use the cool-dark-dry-place method with great results. In fact science has shown no significant drop in germination rates using this method for the first year.

Theoretically, marijuana seeds can last for many decades if stored properly. We know for a fact that scientists have unearthed other viable seeds that were many hundreds or even thousands of years old. It is said that sorghum seeds will keep for 20,000 years and barley for 2,000 years!

A word of caution, virtually all seeds will realize a smaller germination rate over time. This is normal. In other words, if you properly store 100 seeds for 10 years, a smaller percentage of them will germinate than if they were fresh. One thing is for sure though, your seeds will remain viable for far longer if stored properly.

Seed moisture content: Before storing your seeds, it's important that their moisture content is between 5%-8%. If you buy them from a seed bank, you are probably all set but if you produce your own, make sure they are nice and dry before storing them. I'll leave the seed drying method primer to someone else.  Mechanisms of seed longevity:


 * Dormancy - seed is in a physiological stasis, reducing metabolic activity.
 * Seed vigor - enables seed to remain viable. Factors that affect vigor are the genetics of the seeds and how well fertilized the plant from which the seed came was.
 * Seed resistance to microbial decay- some seeds are just more predisposed to decay.
 * Physical and microbial characteristics of it's storage location - Read below for physical characteristics but make sure your container is sterilized to reduce chance of harmful microbes being there.

Containers
Plastic containers are a no no, including ziploc bags by themselves! Plastic will allow air and mositure in. Glass containers are by far the best storage container. Mason jars or the wire bale air seal glass jars have been shown to be the best seed storage container. Some seed companies sell those foil pouches to store seeds but a study conducted in Spain proved conclusively that mason jars or wire bale jars work way better. However, those foil pouches can be great to use if you then put them inside the glass jar because the foil also blocks out light.

Storage Conditions
 Here's a bit of trivia 
 * Oxygen - A low oxygen environment is crucial to long term seed viability. Exposure to oxygen will cause a much more rapid deterioration of seeds. Low oxygen can be achieved by simply keeping them in an air tight jar. Vacuum sealing is fine but not always needed. If the seed moisture content is above 10%, then vacuum sealing will definitely help but if the seed moisture content is below 10%, studies have shown no noticeable increase in viability from vacuum sealing. So no need to go out and buy a vacuum sealer but if you have it, go ahead and use it.
 * Temperature - Low temperatures slow down the metabolic process of the seed and is of prime importance in good storage. 0 degrees Fahrenheit has been shown to be the optimum temp. Anything below 28 degrees is good but 0 is best. Lower temps though can harm a seed.
 * Light - Exposure to light will cause faster deterioration in many kinds of seeds but not all kinds. While I could not find specific data on MJ seeds, I figured since it doesn't hurt, it's probably a good idea to keep 'em in the dark.
 * Use of Silica gel packets - Silica gel packets are an excellent addition to your storage container. They can absorb any stray moisture and help keep things dry.
 * Condensation - Condensation is bad for seeds. Regular opening and closing of your freezer can lead to condensation forming. That is why placing them behind a double barrier will help if any condensation does form. For instance putting them in a ziploc, foil lined seed pouch inside a mason jar is good. It's also why a silica gel packet is a great idea in your container.
 * Humidity - A humidity level of higher than 5% but less than 10% is desirable. Anything higher, will lead to faster degradation and anything lower can lead to seed dessication (drying out).
 * Seeds can contain harmful fungus that never bothers anything and lies dormant unless you store your seeds wrong or screw up your grow and then they rear their ugly head. Also this fungus can be passed along to the plant and subsequently to their seeds and lie dormant there. So basically you could go a while with no problems and then one mistake can cause the fungus to pop up. There was this scientist in South Africa who proved this. I think this is why some seed germination protocols call for dipping your seeds in a 1 part bleach 9 part water solution and then rinsing well before trying to germ them. Some people also use a hydrogen peroxide dip for the same reason I think.
 * There's an international standard of 0 degrees F or -18 C for seed storage?
 * A nutrient rich environment increases genetic variability. This means the chances for a really special "super seed" to be produced is greater if your nutrient concentration is higher. So if you plan to grow your own seeds, use as high a nute concentration as your plants can tolerate. Decreased nutrients also reduce seed weights and total number of seeds.
 * Thawing - There seems to be some evidence that seeds should be removed from the freezer a couple days before germing them.
 * Quick or excessive drying of your seeds can lead to seed deterioration and so can drying at elevated temperatures like in the oven or in intense sunlight.

References:
César Gómez-Campo,PhD. Risk of Inadequate Seed Storage Containers [http://www.seedbiology.de/structure.asp#structure1 Seed Biology and Structure]

Seeds handbook: biology, production, processing, and storage, Chapter 5 By B. B. Desai  Robert Connell Clark  - Seed Anatomy

Global Seed Vault [http://books.google.com/books?id=0VKWUrLJtb4C&pg=PA532&lpg=PA532&dq=seed+exposure+to+light&source=bl&ots=n4VI-3vQ_p&sig=suUCYEML8Hd-zNh_or78nKjxu5c&hl=en&i=CJDaStT2GtCV8AaQnYW3BQ&sa=X&oi=book_result&ct=result&resnum=19&ved=0CHAQ6AEwEg#v=onepage&q=seed%20exposure%20to%20light&f=false Handbook of Seed Science and Technology] by Dr. A.S Basra. (c) 2006