huge foliage on potato

[hawthorns]

i planted maris piper main grop spuds out in mid to late april. i have them in potato grow sacks and plastic trugs i have feed them with comfrey tea.

the foliage is 3 ft tall and is very difficult to support. they are just about to flower but are not due for pulling until august.

why is there so much foliage please advise.

[Alice]

Sometimes I think if they are overfed they produce huge top growth.

[jamesp]

i grow the same variety every year, no matter wot you do they seem to produce large foliage, I planted mine in march and have been picking them for a month, I just get my hand in and find the tasty small spuds and leave the plant to grow on.