storing_seeds_and_tubers.txt

Storing tubers (potato, Jerusalem artichoke, ...)

Optimal storage of horseradish: 0° celsius at 90-100% humidity, stores for up to 12 months
Optimal storage for potato: 7° celsius at 85-100% humidity, stores for up to 8 months
Optimal storage of parsnip: 0° celsius at 90-100% humidity, stores for up to 6 months
Optimal storage for Jerusalem artichoke: 0° celsius at 90-95% humidity, stores for up to 5 months
Optimal storage of beetroot: 0° celsius at 90-100% humidity, stores for up to 5 months
Optimal storage of carrot: 0° celsius at 90-100% humidity, stores for up to 5 months
Optimal storage of salsify: 0° celsius at 90-95% humidity, stores for up to 4 months -so useless-

Storing bulbs (onions, shallots, garlic, ...)

Optimal storage for onion: 0° celsius at 65-75% humidity, stores for up to 8 months
Optimal storage for garlic: 0° celsius at 65-75% humidity, stores for 7 months
Optimal storage for shallot: 0° celsius at 90-100% humidity, stores for just 5 to 14 days -so useless-

For seeds:
Seed requirements vary per species and sometimes even per cultivar, but basically, you'll want most seeds to have a moisture
content of 4 to 8%, and have it stored at 0 to 5° celsius. Some seeds (like onion, lettuce) are best stored at even lower 
temperatures (under -18°C). Make sure you have them dried ("equilibrated") before storing them at such low temperatures. Also 
take note that some seeds require stratification -thus being subjected to a temperature between 1 and 3° celsius for 1 to 3
months- to allow them to germinate.
Storage time is between 1 and 5 years, depending on the crop. 

More info at:
https://en.wikipedia.org/wiki/Stratification_(seeds)
http://www.gcca.org/wp-content/uploads/2012/09/SeedsVegetable.pdf
https://www.kew.org/sites/default/files/09-Seed-air%20moisture%20relations%20web.pdf
http://extensionpublications.unl.edu/assets/pdf/g2090.pdf
https://www.agric.wa.gov.au/fruit/storage-fresh-fruit-and-vegetables?page=0%2C2
http://www.newrootsurbanfarmers.com/blog/2014/9/9/the-science-of-vegetable-storage
http://www.yara.co.uk/crop-nutrition/crops/potato/key-facts/agronomic-principles/

In practice:
The optimal storage conditions are just to be taken as a guideline, since you'll generally not be able to reproduce these
conditions fully (you could reproduce the conditions fully by using a refrigerator or freezer but that's not worth the energy
costs, at least not for tubers/bulbs -it's a different matter for seeds, since these take up much less space and you generally
have a bit of unused space in your refrigerator anyhow - ).
What can you do to reproduce these conditions ?
Basically, you may have following options at your disposal:
you (unheated) garden shed, your greenhouse/cold frame (unheated but generally frost-free), your house -attic or cellar-
(partially heated), your refrigerator (actively cooled).

For tubers and bulbs:
Store in a garden shed, cold frame or cellar in a plastic bag with holes in it and which has been sprayed with water untill it's
time to plant them out (once the environment/soil reaches a temperature of 10°C or above = germination temperature for the
tubers/bulbs).You may want to place a thermometer in your cold frame/cellar/shed and check it now and then to ensure temperature
doesn't exceed 10°C, and when it does, plant it out immediately. Also make sure you have the tubers/bulbs cleaned/dried before
placing them in the plastic bag.

For seeds:
First, reduce the moisture level by placing the seeds in a sealed mason jar with a dry material (such as salt, sand,  ...) under
it. The seeds are hereby best placed on a disc with holes in it above the dry material. Another possibility is just to put them
in a dry paper bag or paperboard shoebox and keep them there untill they're dry (4-8% moisture level). Then, place it in your
cellar (if this has a temperature of 1-3°C for most months -autumn, winter, spring-) or refrigerator. Make sure you keep it in a
sealed container or sealed plastic bag so that the moisture level isn't increased -cellars and refrigerators typically have high
moisture levels-. If you keep it in your cellar, place a thermometer in it and make sure you plant out the seeds once the
environment/cellar has a temperature of about 4°C.