What time do you cover potatoes, when the plant comes up or after it flowers?
Here in Belgium, where it seems that 1/4 of the country farms potatoes since centuries.... All the farmers use planting machines that "mound up" as part of the process...
So we who garden, enrich the soil with compost and cow manure. Plant in a 10cm trench our seed potatoes and right away "mound up" 15cm high. After 7-10 days they burst through ! A glorious sight!
Hope this helps
Peter in Brussels