Answer: The "Madness" series of petunias is a group of hybrids, so saved seed, if it germinates at all, will not produce plants that match the parents. In most cases any seedlings from hybrid petunias are nothing at all like the parents and far inferior. Nearly all the petunias sold today are hybrids. If you want to start petunias from seed it is better to purchase the seeds of a named variety you like.
Dianthus include many different types of carnations and pinks as well as the biennial "Sweet William." Again, if it is a hybrid the progeny will generally not match the parents. However, if it is from an open pollinated seed strain, you might have very good success. Wait to harvest the seed until it is ripe and about to burst out on its own. If this is a perennial plant, you can also propagate it by tip cuttings and division.
Good luck with your experimenting!
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