I compiled a bunch of references while researching Potato Onions which are posted below. It is also available as a The Historic Potato Onion- A compilation of early references, which also has links. First though, I have some notes on my impressions and observations on reading through these references. Note that there are many different planting dates and methods of cultivation. That is to be expected, I suppose, given the widely varying geographies that the authors are referring to. See also my previous detailed blog post on Potato Onions, for more details about the onions and their culture, which is probably a better place to start your Potato Onion adventure if you are new to them.
Apparently planting smaller Onions makes fewer, but larger Onions than if larger Onions are planted. I believe what is usually being referred to here is as follows. The Potato Onion has a number of “eyes” growing inside of each Onion. I believe each of these “eyes” probably forms a new bulb each of which also has more “eyes”. The larger Onions have more eyes and therefore produce more bulbs when planted although of smaller size due to competition within the plant itself. The smaller Onions having fewer eyes produce fewer Onions but larger ones due to decreased competition for soil resources. There are also however references which say that one small Onion will grow into just one large Onion. I don’t think I have ever seen this happen with the yellow potato Onion variety that I have, so I suspect that it is either incorrect or that there is a variety which does behave this way. It is also possible that I just have not planted small enough sets to observe the one-small-into-one-large phenomenon or, further, that I have observed it and simply forgot. I will be observing the results of growing different sizes of bulbs more closely this year. The idea, as some authors mention, is to grow the right proportion of large and small bulbs to assure larger ones for eating while yet retaining enough small bulbs for good seed. Potato Onions often have internal division where the walls of skin between the “cloves” or main “eyes” have dried off. Some mention is made of dividing them along these lines for planting. I have done so, but not in a very observant manner. Read more »