I’ve seen such roses (but in smaller sizes) used in Irish crochet. The idea is not complicated, and I was able to come up with my own pattern. For the roses shown, I used cotton yarn (can’t tell the size and brand as it’s been in my stash forever).

I can picture a beautiful cushion with such rose bouquet on it. Another idea would be a table runner; something similar to this one. Or, perhaps, these roses could be incorporated into a gorgeous afghan (that would be a lot of work though).

As you can see from the pattern, I used different amount of double crochets (15, 16, 17, and 18) for the petals. That’s because I wanted the petals to be of different sizes. Also the place where the petals are attached with a slip stitch can be slightly different.

You may end up with a bit of chain left, which is not enough to make a petal. In that case, just wave it in on the wrong side of the rose.