• How long do seeds last?

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    Someone asked me just the other day… How long do seeds last? They always say packed for (insert year)… Are they still good a year later? Two years? Ten years?

    Tray of tomato seeds

    Tray of tomato seeds

    Good question! But no good answer, unfortunately. I’ve heard of seeds being discovered in ancient tombs that still germinate and grow! Yet I’ve also had packages of seed from the most recent year that don’t do anything at all. I think that there’s a lot that goes into it. 

    Here are some of the things that I know can affect seed viability:

    • Type of plant. Some plants have notoriously hardy seeds (fox gloves and poppies come right to mind) that can just weather almost any kind of mistreatment. Maybe because of their size or durability of their casings? I’m not sure. Others just have no staying power at all and pretty much fail altogether after a year or two (I’ve had a tough time with romaine, specifically).
    • Storage. Freezing temps, humidity or downright dampness are not good friends of seeds. Try to store your seeds in a dark, dry location that stays at constant room temperature like your coat closet. It’s tempting, but don’t store them in the greenhouse or the garage. 
    • Preparation conditions. If you’re harvesting your own seeds be sure they get completely ripe before you harvest them and then completely dry before you store them. 
    • Planting conditions. Planting seeds too shallow or too deep can mean that none or few germinate. As a general rule of thumb, if I don’t have planting depth instructions, I plant seeds at a depth of about the seed’s height and half again. Very fine seeds often don’t have to be covered at all, just sprinkled over the soil. Also, some seeds require certain conditions to germinate. For example, lettuce seeds germinate most reliably in colder temperatures while other kinds of seeds will only germinate if the soil is consistently warm. Some seeds require some chilly nights before they will germinate. 

    What’s the best way not to waste your pots, soil, fertilizer and time on questionable seed? 

    If you know your seed has gotten frozen, overheated, wet or crushed, maybe just chuck it and buy fresh seed. But if you’re not sure about the seed and don’t want to waste it, maybe give it a try in a tray and see what it does! Starting the seed in a tray is a faster than starting it in starter pots, plus you don’t have a bunch of empty pots if your seed is not very productive. Trays often also save space on the greenhouse shelf. (I start almost all of my seeds in trays these days, good or questionable.)

    So that begs the question… How good is seed that you get at the community seed exchange? 

    Well, that’s also a good question that’s not easily answered. Many of the seeds I’ve traded for at my local exchange have had a very good germination rate! But maybe I have just been lucky. You never know what preparation and storage conditions were like at someone else’s house. 

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