They need to be covered with soil, so best to split them and replant, as Nut says, further apart. No point in covering with feed, they get their nutrients for next year from the green leaves dying back.
Gardening on the wild, windy west side of Dartmoor.
Let them die back naturally if you can or if you must move them pop into big pots in the sunniest spot you have and then replant deeper and further apart in the autumn.
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In the sticks near Peterborough