Yacon grew great and highly vigorously for me indoors, when I started them in February. When I took them outside in March, wellllllll, the frosts killed them off right quick. So I was much too eager! They resprouted, but as soon as the summer heat hit, they started to wither and die down.
Probably what happened was that I didn’t water them enough. But I didn’t have my mulch yet, and I didn’t have much water to give.
My plan for yacon next year is to:
a) Buy a variety from Cultivariable. I’m learning towards Bogachiel. If any of my crowns have survived (I hope so!), I’ll replant those next year, too. Of course, I’ll also try anything I can get in a trade! 
b) Start them indoors in February and put them outside in March again, but this time, under a hoop house that will provide a significant amount of frost protection. I think I need to start them in February so that they can get large before insects and drought start becoming a big deal in May.
c) No mulch while we have spring rain. Lots of mulch once summer drought hits.
d) Put them in a partial shade spot. That should provide at least ten degrees of temperature cooling, and I suspect they will really appreciate that. If nothing else, the soil will stay moist for longer in the shade.
In general, I’m starting to suspect most “full sun” plants actually prefer partial shade in my yard. Full sun in my yard means about sixteen hours of intense high elevation sunlight. Partial shade means about six to eight hours of that. I know people who buy shade cloth, and I think that’s silly – I’d much rather grow partial shade in the form of fruit trees!
“My yard has too much sun” is a good problem – that means I can get away with planting way more trees!
