ONLY beets give you more than one plant per "Seed," which actually has more than one possible plant in it. Everything else pretty much grows one seed, one plant, if your're lucky. Many seeds never sprout.
I think there is a relationship between root plants. Iris, for example, reproduce by growing new corms, which can be broken off and replanted for more iris. They multiply by two's, so one iris becomes two next year, and 4 the year afterward, etc.
Potatoes are hard to grow from seeds, but pretty easy to grow from the roots that form on whole potatoes. One gives you many at the end of the growing season.
Onions, however, start OUT as seeds which grow into small bulbs, and need to die and regrow year #2 to become the crop that we know and love in our salads and sliced in our hamburger buns. Onion
sets were grown from seed LAST year.
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TOLD you it's friendly here.

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