[RegulatorCountry]

It’s not so much the variety of onion that makes a Vidalia mild and sweet, it’s the soil conditions. You could plant the very same onion in different soil and have it come out tasting much stronger. Sort of like planting hydrangeas in acidic soil versus alkaline soil results in the plant blooming blue, pink or purple. Some people enjoy putting lime on one side of the plant to have a multicolored hydrangea.

[Black Agnes]

True. But supposedly there are part of TX with similar soil content that can grow equally sweet onions. The Texas Sweets we buy seem to be just about as sweet as the Vidalias. Any sulfur content in the soil seems to be the bad thing WRT sweet onions.

[piroque]

It’s not so much the variety of onion that makes a Vidalia mild and sweet, it’s the soil conditions. You could plant the very same onion in different soil and have it come out tasting much stronger.

Correct the soil does make a difference not only in the onions but in watermelons , if ever in Louisiana and you see a Water Town melon ,its the sweetest you'll ever have.