Sweet potatoes are susceptible to frost and need a warm, moist growing season. Sweet potato starts are planted usually 4 weeks after the last hard frost.

Harvest:
Sweet potatoes require from 100 to 150 days to reach harvest. Lift sweet potato tubers when they have reached full size, commonly when leaves and vines have begun to yellow and wither.

For more information on growing Sweet Potatoes, check out this great guide from Harvest To Table:
https://harvesttotable.com/how_to_grow_sweet_potatoes/