When you transplant your roses, be sure to dig a much bigger hole than you think you need (for most types, the planting hole should be about 15 to 18 inches wide), and add plenty of organic matter such as compost or aged manure. This will feed your plant in the years ahead. Some old-timers recommend placing a 4-inch square of gypsum wallboard and a 16-penny nail in the hole to provide calcium and iron, both appreciated by roses.
Choose the pod -- or female -- flower that will produce the seed pod. Remove the petals. Identify the fringe of yellow pollen-producing structures called stamens that surround the central style. Cut the stamens off with small scissors so they will not accidentally pollinate that flower and so that the pollen will be available for planned pollination of other flowers.
A gentle way to clean the rose seeds is to use a Cuisinart or other brand of blender with a dough blending attachment, which is made of plastic and does not have sharp blades. You can blend the rose seeds using this gentle dough attachment for several minutes without any damage to the seeds. Do not use a blender with sharp metal blades as damage to the rose seeds may occur.
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.
When pruning, be judicious. If you prune too hard in autumn, plants can be damaged beyond recovery. Instead, wait until spring, when plants begin to leaf out for the new season. (Roses are often not the earliest plants in the garden to respond to spring’s warming temperatures, so be patient.) Give the plant time to show its leaf buds then prune above that level.
Prepare a pot. Fill the small pot with potting soil. For the best results, replace a quarter of the soil with perlite, peat moss, or vermiculite, or a combination thereof. This will increase air flow and draining, giving your cutting a better opportunity to root. If the soil is dry, water it and allow the excess water to drain out, so that the soil is evenly moist.
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