I wouldn't worry too much. The foliage may have been zapped, but the roots should be fine. I'm not sure if your nurseryperson meant all perennials are like weeds (they are NOT), but this plant most certainly is. There are a great many folks who seriously regret the day they planted houttuynia - it is an aggressively spreading thug and right up there with the worst of the worst - bishop's weed, yellow archangel, mint, etc. I would never, ever plant this one directly into the ground. It needs to be contained.

I'm fairly certain that the roots probably survived. I have been a big fan of Houttuynia for many years. I have extreme shade and most summers we have drought conditions. I am convinced that this ivy would grow anywhere and do well. Yes, it is a bit invasive, but nothing like English Ivy or Mint. How many other ground-covers feature three distinct colors, not to mention the white flowers in early summer? I do notice that all the mail order catalogs have stopped carrying it, so I'm guessing it's aggressive habit has made it unpopular. But then, I'm a fan of Bishops Weed too...

I would wish Hot Tuna was as aggressive as the plants listed above. Unfortunately for me it is not. It is especially pretty planted with something with dark burgundy foliage for contrast. I think it has to be in very moist soil to really spread. Kept dry it barely hangs in there. It certainly can't outcompete the noxious grass weeds we have here so weeds overrun it badly for me.