Can you put daffodils in a vase with other flowers?

Yes, but it is best to condition daffodils separately first. Place them in a separate vase for a day so they can release their sap, which can be harmful to other cut flowers. Afterwards, you can combine them with other flowers in a clean vase with fresh water. If you recut the bouquet stems after a few days, avoid recutting the daffodil stems to prevent them from releasing more sap.