You don't have to overwinter ivy in the garden
The normal ivy in the garden does not need any special protective measures in winter. Only with freshly planted ivy can it be worthwhile to protect it from frost and above all from dehydration in the first year with a mulch cover.
Hibernate ivy in a pot
Special winter storage is not necessary for deeper pots. If the ivy is cared for in the flower box, you should protect the soil from frost by placing the planters on an insulating surface and wrapping them with burlap if necessary.
The biggest problem with ivy in winter is drought. If brown leaves appear in spring, this is the rarest of frost damage, but dried up leaves. Therefore, in dry winters, water the ivy on frost-free days.