Growing roses from seed can be challenging, since the majority of seeds you collect often won't germinate regardless of your efforts. Fortunately, most rose plants produce a large quantity of seeds inside their rose hips, so it usually isn't necessary to achieve a high success rate. Keep in mind that the plants that grow may be different in appearance or other characteristics from the mother plant, especially if that plant is a hybrid of two varieties grafted together.
Alfalfa provides solid nutrition to roses, supplying nitrogen, calcium, iron, phosphorus, and other nutrients, including a fatty acid known to promote plant growth. Work alfalfa meal or pellets into soil around roses (1 cup per large bush; one-half cup for miniature roses). You can also brew alfalfa tea by soaking alfalfa meal or pellets in water. Discover tips on making and using alfalfa tea from the American Rose Society.
Prepare a large hole. You'll need one for each rose bush you're planting. Use a garden spade or shovel to dig a hole 18 inches (45.7 cm) wide and 18 inches (45.7 cm) deep. The measurements don't have to be exact, but a hole this wide and deep will be suitable for most roses. Mix the soil you removed from the hole with compost, and use some of it to form a small mound in the base of the hole. Add some bonemeal or rose fertilizer.
Next fill your trays or pots with the potting soil. You can opt to use 50% sterile potting soil and 50% vermiculite, or half peat and half perlite. When the potting mix is ready in the trays or pots, this is the time to take off your seeds from the towel. Remember the seeds must not be removed from the plastic bag until they are ready to be planted. You lightly dust them before planting.
You may even wish to cut your cuttings down to 3" to 4" and double your plants, but they will be more prone to rot or dry up faster if you let the soil dry too long. The cuttings that are 6" to 8" seem to do much better, and if cuttings are even longer, the water has a longer length to travel up and down, and the cutting may end up more dehyrated with the upper part dying off. So 6" to 8" is a happy medium.
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