There are about as many methods of raising rose seeds as there are for propagating, pruning, planting, fertilizing, etc. Generally, you need to clean the seeds from the hips. Warning- the fibers inside the hips are as irritating as fiberglass. Do not get them on you or you will itch beyond belief. I always shower immediately after shelling seeds from rose hips.
A pairing knife or small scissors can easily be used to slice open the hips and pry out the seed. Some people wash them, even sterilize them with a variety of solutions. I've stopped cleaning them simply because in my hot, dry climate, it isn't necessary. Some people feel they require a period of cold "stratification". Some may, but not all do. I"ve had extremely heavy germination with, and without the cold period from the same basic types of seeds. If you're germinating species from colder climates, they may need more cold. If you're germinating HT, floribunda or OGR seeds from evergreen, warmer climate types, they may well not. Ralph Moore, the Father of the Modern Miniature Rose, felt seeds germinated without the cold probably were more evergreen and early flowering. His logic was in Nature, those were the seeds which were likely to be best suited for warmer, longer season climates. He found those which germinated the second year from sewing tended to be once flowering, as if they may be the more cold hardy, most suited for shorter growing seasons. Experiment to see what works best for the types you are attempting to raise and in your climate. My seed are shelled then put into small zip lock type baggies with labels to indicate the crosses, then placed in the fridge to hold them until the weather is conducive for germination.
I hate to keep using the word "generally", but most of this is "in general" because none of this is written in stone. No matter how religious you are about following someone's "rules", Nature is going to thwart your best efforts every time. You can do everything precisely as instructed and one year they'll germinate like grass. The next, they won't. Then, you can just haphazardly shove them in dirt and they come up like grass again. There are so many variables in moisture, temperature, condition of the plants producing the seed, etc., which can help influence success. You can't control them all. In general, most rose seeds slow their germination when temps hit the seventy degree mark. As it gets hotter, they literally come to a halt. Here, that means they probably aren't going to germinate before after Thanksgiving anyway, so I don't plant them until Thanksgiving-ish. I say "ish" because I wait until it begins to cool to that range and (hopefully!) there are chances of rain. Seeds KNOW the difference between rain and hose water. Some will poke their heads up with the hose water, but they explode when it starts to rain.
The seeds are pretty much mature enough to germinate after about 120 days from pollination. I time my last pollination so I can have them all harvested, shelled and in the fridge by October 1, to hold them for two months (approximately), providing them a cold period (just in case) and because I have found here, if I push leaving ripening hips on the bushes past October-ish, the chances of them being eaten by the rodents (squirrels, mice, rats, etc.) which wander through here from the chaparral are MUCH greater.
There are many opinions about what the "perfect" germination media is. But, think about it. Rose seeds have germinated in a wide variety of soils around the world for millennia without any Human intervention. They come up in the junk dirt in my back yard all by themselves. Basically (how's that for a replacement for 'generally'?) you want a soil which remains light enough for the small seedlings to push through it easily; for roots to expand through it easily; which remains moist without water logging. There are seed starter mixes which can work very well, if you can keep them watered appropriately. It's difficult here due to the unusually high, arid heat spikes we have been receiving during our winter "rainy season." I just use the moisture control potting soil I use for everything else and it works just fine for most of them. You only want to cover the seeds between an eighth to a quarter of an inch with soil. You want them covered so they don't scald in case the sun is too brilliant and hot and to prevent the birds from eating them. I made "lids" for my tables out of 1" X 2" lumber with metal hardware cloth stapled to it so air, light and water freely enter, but rodents and birds can't. Once they begin pushing through the screens, I remove them and let them continue growing until it begins raining and I can safely transplant them from the tables into pots, then reuse the tables for this year's seeds.
These are my two seed tables. I think you can see they appear to germinate pretty well.
