When the rose hips are ripe, after about four months, cut them off the bush. Some rose hips will turn yellow, orange, or red, but others stay green even when they are ripe. You can open the hips as soon as harvested or you can store the unopened hips in the refrigerator for several weeks before opening. Then slice the rose hips in half, and open them with a knife. A butter knife will do just fine. Now, dig the rose seeds out of the rose hip with the knife, and throw away the pulp and outer shell.
Water the planted rose seeds well and place them outside in direct sunlight (no need for Grow Lights). If there is still danger of frost, then you will need to place the seed trays in a protected location such as under a tree or patio. You will need to keep the rose seed trays watered and don't let them dry out. After about six weeks, or when the weather starts to warm up, the little rose seedlings will start to sprout. They will continue to sprout as long as the weather is cool, but will stop sprouting when it gets too hot.
Allow rose hips to develop by leaving dead flowers on the plant. The flowers are typically pollinated by insects, or pollinate themselves in some varieties, so there is no need to pollinate by hand unless you are breeding specific plants together. Leave the flowers on the rose plant without cutting them. After they wither, small fruits known as rose hips will develop in their place.
While your cuttings take root, keep them covered and moist. In a garden bed, a simple DIY mini greenhouse does the trick. Just place a bell jar, a garden cloche or an overturned mason jar over the cutting. A clear plastic bottle with the bottom cut out and the cap removed works, too. Water the soil regularly to keep it moist, but not soggy. Your mini hothouse will keep the humidity high inside.
Soaking the seeds is a crucial step if your seeds will germinate properly and stay clear of any diseases. You MUST not mix the bleach with the hydrogen peroxide as this results in a chemical reaction. 3% peroxide for 24 hours is just fine. This is also a good time to perform the water float test. Remove all seeds that float as they might not be viable.
There will be disappointments along the way, when many rose seeds fail to germinate, or perhaps they do germinate, only to die several weeks later from damp-off disease. Sometimes a rose seedling will turn out to be as ugly as sin, or very sickly, and you will reluctantly have to throw it away. Other times they will be just ho-hum, or look too much like its parent, and therefore have no value. But, just when you don't expect it, you might discover that one of your rose seedlings turns out to be very special.