David, I don't know what to tell you.
I purchased three organic Yukon Gold potatoes in early November from a local organic grocery store (*not* Whole Foods). This being late fall by most of the country's standards, I knew I probably wouldn't be able to purchase seed potatoes, so I said, Well, we like Yukon Golds anyway, and the price is certainly right!
I cut them up into two-eye chunks just as we planted them in the little 4' x 4' x 10" frame (a small raised bed). No sulfur dust, no anything. The planting mix is part native soil, which we improved 10 or so years ago with homemade compost, plus new compost and some leftover potting soil from OSH (store brand, nothing special). We also purchased a 2 cubic foot bag of organic potting soil somewhere along the line from Ace Hardware, but I'm not sure where that stuff ended up. It *could* be in the current potato bed, but I just don't know.
Anyway, we planted the chunks into the soil and then watered them in. The plants are now about 15 inches high. I had just enough time today to add a 5-gallon bucket of compost to the bed, which wasn't nearly enough to cover their stems, but it was all the time I had (I'm still on deadline, but needed to come up for air, which is why I'm posting).
As a new grower of potatoes myself, I'd recommend calling your county Master Gardener program with this predicament. Most counties in California have such a program; it's run by the Agricultural Extension service and staffed by trained volunteers.
Good luck with the spuds. Yukon Golds are incredible, aren't they?
Since planting, the Bay Area has had a heat wave (record temps for mid-November) followed by a little rain, followed by the usual cool, overcast weather that's normal for this time of year.