David, I'm thinking your summers are very hot and dry? The nasturtiums should thrive through your summer weather if you keep them watered a bit. I grew them in Salt Lake City for years and they would re-seed in the fall and come up on cue in spring, then bloom all summer. We have at least a month of 100+ degrees F weather there in summer.
Sweet peas are a cool-weather lover and need lots of water. I honestly don't know if their seeds would survive being planted now and going through the summer heat. They may sprout and then die of heat or dehydration. If they didn't sprout, they'd likely be eaten by birds or other critters. You'd be better off to save them in a little glass jar or something else clean and air-tight. Put them on your computer desk where you will see them often? Plant them next year in February or so.
