CactiGuide.com

I've obtained seed of various cold hardy cacti over the years from seed exchanges, mostly Echinocereus of various species. They have been languishing in my seed collection because I've been too intimidated to try to germinate them. I'm a new member here and have been reading through some of the posts on starting from seed, and think I'm finally ready to try my hand at germinating some seed. I have a couple of questions before I start:

How long does the seed remain viable? Some of the seed packets I have are as old as 10 years--Is it a waste of time and materials to try germinating the older seed?

For older seed that may still be viable, I was thinking of sowing thickly to make up for possible reduced viability of seed. Is there a danger in sowing cactus seed too thickly?

Thanks in advance for any advice you can send my way!

You could soak them in a sugar solution. Here is a youtube video by San Pedro Mastery on how to do that: https://www.youtube.com/watch?v=joFOecWEXow

A lot of cactus seed remains viable for a very long time. I can guarantee 0% germination if you never plant the seeds.

Soil and pots are cheap, so no need to overplant— depends on the species, but maybe not more than 20 seeds in a 2 inch square pot.

Some seeds like Strombocactus have a short shelf life, probably some Coryphantha, and most Euphorbia and Avonia seeds, but a lot of cactus seeds have a long shelf life.

Don’t overthink this. Get some soil, wet it, put seeds on soil, put in plastic bag and wait a week or two. You don’t need to sterilize the soil, etc.