There is a simple method for growing rose plants from seed. Fall is a good time to start this project, and it’s especially good to wait until after a hard freeze to collect the rose hips from your rose plants. If the hips are clipped off the plant before it is dormant, it may encourage the plant to put on tender new growth that could be damaged during winter.
The first step in growing roses from seed is to gather the rose hips. Rose hips are the seed pods that form when roses are allowed to mature on the plant. Depending on the type of rose plant, rose hips will generally turn orange, yellow, red, or brown when they are mature. Gather rose hips that remain on the plant and do not collect those that have fallen to the ground.
Next, cut each rose hip in half and remove the seeds. Rose hips may contain anywhere from one to forty seeds per hip. Once the seeds are removed from the hips, rinse off as much of the pulp as you can by gathering a handful of the seeds in your hands and rubbing them together under running water.
Once the pulp has been removed, place the seeds in a plastic bag along with some damp peat moss and keep them in a warm room for about four weeks. If some mold appears within the bag, that’s fine. It will help break down the hard seed shell.
After four weeks, move the bag of seeds into the refrigerator for another six weeks of cold stratification. This six-week cold stratification is an imitation winter for the seeds.
The next step is to plant all the seeds in a flat. Plant each seed about a half inch deep and an inch apart. Keep the planting medium moist but not soggy while the seeds germinate. You may need to spray the seedlings with a fungicide if any mold develops. Roses are fungus magnets, and lack of disease resistance can be an issue with seed-grown roses.
When the seedlings develop their first true leaves, they can be potted up. After they are potted give them a weak dose of fertilizer with every other watering.
Do not expect that seed-grown rose plants will be identical to the parent plant. Seeds from any one plant will produce a wide range of bush shapes, from climbers to shrubs or ramblers. Flower color will also vary, with pink being the most common. To duplicate a rose plant exactly, it can be propagated with cuttings, but growing them from seed is a fun gardening experiment.