HelpfulGardener.com

Recently I was in southwestern Utah (Glendale) and harvested hips from
a wild rose that had both yellow and orange blossoms last May. I also
got cuttings which I am attempting to root. The rose hips were mostly
yellow and red with still some green; I have been exposing the hips to
sunlight daily in an air-conditioned house and they are now mostly red
and dark orange. I have read in several places that rose hips should
be collected after the first frost. Does that mean that they must be
frozen briefly before the seeds are viable? One writer referred to a
procedure called "stratification" , which is placing the seeds in peat
moss in the refrigerator for 45 to 60 days before planting. This rose
has only 5 petals and a delightful fragrance, blooming only once a
year according to the lady who lived nearby.

The process is called stratification. It is used to simulate changes in season to trick the seed into germination quicker. A rose seed left up to it own devices may take up to seven years to germinate. The process I use involves moving the seeds from a warm place to a cold place ie: heated greenhouse to fridge in a two week rotation for 2 months starting December and planting the seeds by the end of January. I don't tend to put the seeds in peat rather opting for a mix of ground up vermiculite and cheshunt compound, using just enough compound to soak the vermiculite. The vermiculite acts as a conductor and the cheshunt stops the seeds from rotting. Hope this is of some help.