I grow my own onions from seed every year. I tried sets the first year but they didn't do much. It seems whatever they sell for sets are not good growing onions. I get Ailsa Craig Exhibition and Red Wing onions from Pinetree Seed and start them inside under lights by early Feb. I transplanted the seedlings last week into the garden.

I don't know about wood ash, but they do like a lot of compost and a lot of water. The biggest onions I ever grew came about when we had a very rainy summer. So now I make sure to not be stingy with the hose.

The best onions I ever grew came right out of the compost pile. Come to think of it, all my best produce has come from there! We throw a little wood ash in the piles, the rest just gets scattered all over the yard.