To harvest almost any flower seed you need to let the seed pod grow to its full size and often it will start to become dry or change a slight color. Just keep an eye on your nasturtiums and you will see some changes in the seed pods. I personally haven't harvested nasturtium seeds, how about any of you other gardeners? Can you give us some first hand knowledge?

Perennial sweet peas can be purchased at two seed companies that I know of: they are Shepherd's Garden Seeds (www.shepherdseeds.com) or Territorial Seed Company (www.territorialseed.com)

You could also harvest some seeds from perennial sweet peas that are growing and you have access to. I picked mine a few years ago from some that were growing along side the road. They didn't do anything the first year I put them in the ground. I thought they were duds. But after a winter in the ground the next spring they grew, not much but they were growing. It was the following year when they really took off. Try to pick them when the pods are full and starting to dry. Don't wait too long or they will have fallen to the ground.

Hope this all helps, Bye, Diane