Hi Barb,
I'm a paper preferred person. For a couple reasons. One, I originally didn't have anything to put seeds in to trade them and my hubby clipped up an envelope and I realized I could make pkts. from scrap paper. This appeals to my cheap side, lol. Two, I once killed seeds by pkging in plastic too soon. I had though they were out drying long enough, but I was wrong. Seed can look dry, but if the percent of moisture isn't below a certain point, they will die. If there is a high percent of moisture left, you will actually see mold develop. So I like to be safe and just use paper.
I will use plastic for tiny seeds though like poppy seed.

There aren't many seeds with a real short viability. Allium(onion family,) some herbs like parsley, and I'm drawing a blank right now, lol.
There are some seeds that should not dry out or will lose viability quickly. The rose family which includes roses, apples, and other fruits. Also woodland plants that are spring ephemerals need to be planted immediately.

Most seed though stored in a cool, dry, and dark spot will stay viable for quite sometime. I sowed seeds from 2004 and 2005 this past winter and had no trouble with most all of them.
Remy

this link has length of viability for a few varieties.

Here is a link that might be useful: seed viability

Thanks Remy and Jaynine for the response. I am just learning about viability of seeds and it made me wonder. I know adedium seeds need planted within 90 days of collecting. I have found out also gas plant needs planted right away. I was wondering about other seeds too...Sure is a learning experiance this gardening stuff. lol Barb

Hi Barb,
here's some dictamnus growing info.

Here is a link that might be useful: dictamnus germination

i wish i had known that, i had some from fall, and still haven't planted them, saving them for winter sowing. ~Medo

Here is a link that might be useful: Barehanded Totally Nutso Gardener!! **Big Grinn**