Seed viability

[charlpic]

This probably depends on how good the seeds were stored and everything but...

Would you buy seeds (let's say Mamillaria nana as an example) that are more than 20 years old ?

Is there some genuses that you would basically want older seeds instead of fresh ones ?

My question is because I found a seed dealer that provides the age of the seeds and some are pretty old.

[Pilif]

Well,
most cactus seeds remain viable for a very long time,
mainly because they have to 'wait' for the right moment to germinate, which can, in some occasions, take a very long time(copiapoa for instance). Almost all seeds have an incubation time, an amount of time they should be stored before being sown. In nature this is to prevent seeds from germinating before they are spread (i.e.: they have time to get out of the fruit en be eaten, or be carried by the wind,...).

there are of course also some cacti that should be sown as fast as possible (frailea are notorious for this), because they lose their viability very fast.

I myself keep almost all the seeds I get for half a year before sowing them, with most species the difference isn't huge, but I get generally better results.

20 years is rather old though, certainly for small things such as mammillaria; after 5 years I would't count on a high germination rate.

What would you/the seed dealer consider pretty old?

[iann]

I don't know about "most" but certainly "many". There is a definite minority that lose viability within months. A good rule of thumb seems to be that tiny seed goes off quickly.

It would have to be a fairly special find to pay money for 20 year old seed. It is definitely possible to store seed for this long and I wouldn't be at all surprised if just keeping it cool and dry would preserve it for 20 years, but there is a good chance it is totally dead.

There is lots of documentation of cactus species that germinate better after some storage. Just storage, no special treatment. Some Ferocactus, some Opuntias, probably some Echinocactus, and no doubt more. Lithops seed, and many other mesembs, shows some dormancy at the time that the capsule first becomes ripe. This manifests as waves of germination several weeks apart, but after about 6 months the seed all pops up together.

[charlpic]

What would you consider pretty old?

I would definitively say 20 years old is... old. But then, I'm pretty sure the conditions they were kept in were very good.

I sowed my first seeds in July last summer so I can't rely on my own observations. The only seeds I sowed that I know their age are Opuntia and Hylocereus from fruits I bought at the grocery store and I had surprisingly good (imo) germination rate.

But you guys came up close to what I tought... could still be viable but probably too old.