How do I set up a swap list?

The first thing to do if you have any seeds for swap is list them in your swap list so that others can see them – if you already have them in your stash, the only thing you’ll need to do is mark as “available for swap” (go to the edit stash page and check the box “This item is available for Swap or Trade” right at the bottom of the page).
Now you have a trade list! From here, you can either wait until someone who is after that plant or variety contacts you about a swap (your plant will appear in their Swap Matcher on their Wish List page if they have that plant listed, or they might just find you by browsing around the plant pages as you’ll be listed there as well).