Planting depth

I am planning on transplanting my Kniphofia to a sunnier, drier spot than where it is at present. Currently the rhizomes are partly above the ground surface. I'm not sure if this is correct as it makes them vulnerable to frost unless covered.
When I replant, should I replant them beneath the soil surface? If so how deep should they be planted? Thanks for your time.

Re: Planting depth

Reply from Kathy C

Hi, Ronald,
Plant to the crown of the plant - where stems meet root. Your right that the rhizomes should be under ground. You can move them in autumn and then mulch them for winter.
Kathy C