It depends on how quickly your soil heats up, which can depend on soil moisture level, hours of direct sun and mulch thickness. Use a soil thermometer to get an idea of your soil’s temp characteristics. Raised beds supposedly heat up more quickly, but if they are heavily mulched, maybe not so much.
You can also plant in the heat of the summer so that when the soil cools and days shorten, the tubers will form fine. These can be left in the ground in some zones (and areas protected from voles) until December.