Fertilize the roses. After they are established, roses should be fertilized a few times per growing season. Use fertilizer (either liquid or granule) in early spring, when you see the first few leaves sprout. Use it again after the first bloom, and again if there's another bloom. Stop fertilizing the roses at the end of the summer, just before Labor Day.
The ripened rose hip is then placed on a clean cutting board and cut in half to remove the seeds. Place the seeds in a clean container. Add some diluted bleach to kill off any bacteria and fungus spores. You can make the bleach by mixing drinking water with two teaspoons of household bleach. Stir the seeds well before rinsing them and using bottled water to remove all the bleach. To further clean and disinfect the seeds, put them in the container and add some hydrogen peroxide. The seeds can be soaked for up to 24 hours before rinsing them with clean water to clear all the hydrogen peroxide.
The next step when you grow roses from cuttings is to use a pencil or metal probe push down into the planting site soil to make a hole that is deep enough to plant the cutting up to about 50 percent of its overall length. Place the cutting that has been dipped into the rooting hormone into this hole. Lightly push the soil in around the cutting to finish the planting. Do the same thing for each cutting keeping them at least eight inches apart. Label each row of rose cuttings with the name of the mother rose bush it was taken from.
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.
Everybody has a story to tell of how their grandma would stick a piece of rose stem into the ground and then place a Mason Jar over the stem to make it grow. There are tales of how the early American settlers of the 1800's traveled to the far reaches of the wild west in covered wagons, with grandma bringing along "starts" of her favorite roses from back home. Perhaps the treasures of these "monsters on wooden wheels" were raided, and they discovered the Yellow Rose of Texas hiding under the bonnets of the women. Or maybe the settlers used their precious "starts" to barter for provisions along the endless dusty trails.
Water. Irrigate roses deeply but infrequently, applying water directly to soil using soaker hoses or drip irrigation. Water needs vary based on weather and soil, so check soil with your finger. Water often enough to create consistently moist soil – not overly wet, not bone-dry. To prevent diseases, keep foliage dry, especially if you must water late in the day.
Español: cultivar rosas usando semillas, Italiano: Coltivare le Rose Usando i Semi, Português: Cultivar Rosas a Partir da Semente, Русский: вырастить розы из семян, 中文: 用种子种玫瑰, Deutsch: Aus Samenkörnern Rosen ziehen, Français: faire pousser des roses à partir de graines, Nederlands: Rozen kweken uit zaad, Bahasa Indonesia: Menanam Bunga Mawar dari Biji, العربية: زراعة الورود من البذرة, Tiếng Việt: Trồng hoa hồng từ hạt, 日本語: バラを種から育てる, 한국어: 씨앗으로 장미 기르는 방법