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.
After the rose seeds have soaked overnight, rinse them in a strainer and place them into the blender with at least a cup of plain purified water (making sure all seeds are covered), and turn it on for a few minutes. It usually doesn't chop up the seeds, but rather, it will clean off the pulp remaining from the rose hip, which would otherwise mold if left on the rose seed. You may see a few seeds chopped up, but those usually aren't viable anyway. Flush the rose seeds again through a strainer using fresh purified water.
It is generally agreed that "old roses" include species or wild roses; albas; Bourbons; moss roses; China roses; Noisettes; Portland roses; rugosa roses; Scotch roses; centifolias; hybrid pimpinellifolias; damasks; gallicas; hybrid perpetuals; tea roses; and musk roses. Those classified as modern rose varieties are hybrid teas; floribundas; polyanthas; grandifloras; miniatures and dwarfs; modern shrub and landscape roses; climbers and ramblers; and rugosa hybrids.
Pick a sunny spot to plant your rose cuttings. Where you place your cuttings is especially important if you’re planning on growing them outdoors. Choose a spot that’s sunny but that’s not in direct sunlight — you don’t want them to dry out. Putting the rose cuttings in a pot or container is alright as well, just make sure the container is deep and wide enough for your rose cuttings to grow.
Pests and diseases: Prevention is the best way to avoid pest and disease problems. Start with disease-resistant varieties, keep plants in healthy condition (well fertilized and well watered), maintain good air circulation, keep foliage dry, and remove any diseased foliage or spent flowers. For Japanese beetle grubs, use beneficial nematodes or Milky Spore (Bacillus popilliae). Rose Rx is effective against scale, spidermites and aphids. For more information, see the Pest and Disease Finder.
I have successfully taken rose cuttings with both new and old wood. It is important to let the new stems sufficiently mature. The new wood is usually mature enough after the stem has just finished blooming. If you don't let the stem mature enough, then it usually becomes limp and will die before you can get it to root. I take cuttings from new rose stems in the spring right after the first bloom cycle. Then in early to late fall (in Southern California) I prefer to use more mature or old wood. When using old wood in the fall, I will remove the rose cuttings from the Mason jar, baggie, or mister, after only several weeks since it is cool enough then for them to root on their own as long as I water them daily.
Grow your roses indoors, alternatively. You can also raise roses in a greenhouse. You’ll need containers that are at least 9 inches (22.9 cm) wide. Spread 1 to 2 inches (2.5 to 5.1 cm) of small pebbles at the bottom of each pot to ensure good drainage and fill each with halfway with well-draining soil. Plant the roses just beyond the graft point and then water well.
Caring for rose bushes is important to their overall health and vigor, especially when it comes to watering. Roses require at least an inch of water weekly throughout their growing season, beginning in spring or following spring planting. While overhead watering is suitable before the onset of new growth, it is often better to water these plants at the soil line using soaker hoses or similar means. Rose bushes are very susceptible to fungal diseases, such as black spot and powdery mildew, especially when their foliage is kept too wet.
Growing roses from seeds is not the fastest method for propagating roses but has several advantages. Roses from seeds take a little longer but then you end up developing a new set of varieties. Professional hybridisers select a new line of easy to grow and disease resistant rose to propagate. However, for you, each seedling will be a surprise when they finally bloom. It is like opening your birthday present when you were a kid. You never really knew what to expect! That is the same feeling seeing those little seedlings opens up for the first time.
The rose seeds can be planted right away if you have harvested them as late as November, December or January (in Southern California) or early spring after danger of frosts in your area. Place the rose seeds about one-half inch deep in a very light mixture of 50% sterile potting soil and 50% vermiculite. Some rose hybridizers use Sunshine Mix #4. You can use small pots or shallow trays to plant your seeds, whatever works for the space you have, as long as they have good drainage. Nursery flats work well for this. Lightly dust the rose seeds with RooTone or Captan before covering with soil. And then dust the top of the soil again, which will hopefully help to prevent damp-off (a disease which kills young rose seedlings). Amateur rose hybridizers concerned with toxic chemicals may want to periodically spray the seed tray with diluted peroxide and water instead of the more toxic Captan.