Treat just like cut flowers! Here are some other tips:
This gives some tips on how to keep it in a vase: https://www.flowershopnetwork.com/blog/keep-cut-holly-fresh/
I have always stuck it in a vase of water or used water soaked green oasis foam in the lower depth bowl display.
Always re-cut foliage and soak in water overnight before arranging. I alway Hammer the base of cut to expose the fibres too as that helps in take up of water.
Re- cut as you arrange your vase.
I've cut holly and stuck it in a vase for decorating. I didn't even give it water and it lasted forever.
Keeping holly looking alive and vibrant is a little tricky. Think about it! First we cut it from it life source and then we put it in a house that is warmer than its natural environment.
The key to keeping it vibrant is to create an environment as close to nature as possible. First, keep it hydrated. If possible, put it in water or at least mist the foliage every day. You can create wreaths and other holly arrangements with floral foam soaked in water. This will keep your holly hydrated. The second key is to keep it cool. Holly will do better if the room is slightly cooler than normal and away from any blowing heat source.