I'm no expert Emma, but I think any real berries are going to dry and shrivel up because they contain liquid. I collected some real pretty red berries last year from a bush along side the road but I had them in water the whole time. They did last that way, at least for a few weeks, then the leaves turned brown and it was time to get rid of them. I've never tried the "drying flower silica sand" or whatever they call it, but you might want to use that. Either try calling a florist for the info or do a search on the web for dog-wood tree berries and see what you can come up with. Sorry I couldn't be of more help.