How to grow:
Before growing roses from seed, the seeds must go through a period of stratification. This is cold, moist storage that prepares the seeds for germination.
Cold treatment:
Chill your seeds in the refrigerator for about six to ten weeks to help them germinate faster after planting. However, you must be careful not to keep them cold for too long as they can germinate just in the refrigerator. Place your seeds on a paper towel before moistening them. Use half purified water and half peroxide to prevent mold. You can then place them in a zip-lock plastic bag, mark the date and variety, and then place them in the refrigerator at 1 to 3 degrees C. The paper towel should remain moist throughout the period. You can check occasionally to see if re-moistening is necessary. Make sure you do not freeze the towel.
There are other ways to stratify the seeds, such as planting them in a tray of potting soil and refrigerating the entire tray for weeks. The tray is usually enclosed in a plastic bag to keep it moist.
Planting Your Seeds
When you think your seeds are ready to plant (6–10 weeks), remove the bag from the refrigerator if you chose this stratification method. You will need shallow trays or small pots to plant your seeds. Whatever works between the trays and pots is fine as long as they have good drainage. The ideal size of the trays or pots should be 3–4 inches deep.
You can use separate trays if you are planting seeds of different rose hip varieties. You will need to follow your labeling from harvest to treatment to planting. The name of the rose bush and the planting date are some of the details you will need to include on your trays or pots.
Next, fill your trays or pots with the potting soil. You can choose to use 50% sterile potting soil and 50% vermiculite or half peat and half perlite. When the potting soil in the trays or pots is ready, it's time to take the seeds off the towel. Remember, the seeds must not be taken out of the plastic bag until they are ready to plant. Before planting, dust them lightly.
Place your seeds about ¼ inch deep in the soil and dust the surface again to prevent damp spot disease, which kills the seeds. Water them properly and place them outside in direct sun. In the event of frost, it is best to place the seeds under a tree or in a sheltered part of the patio for protection. Grow lights are not necessary.
Keep the soil pots or trays watered but not soaked. Do not let them dry out, as this could affect the germination of your seeds.
Watch for germination.
After about six weeks, the first two seed leaves will begin to emerge before the true leaves can emerge. The seedling must have three to four true leaves before it is ready for transplanting.
Planting your seedlings
When the seedlings are a few inches tall and have at least three true leaves, they are ready to be transplanted. You can transplant them into a 10cm pot of your choice. You do not need to plant all the seedlings, just the healthy ones. You can monitor them on the tray and only transplant them when they have outgrown the tray.
You will need to monitor the seedlings as they grow in their new pots for color, shape, bush size, branching and disease resistance. Roses with weak, unhealthy or unsightly flowers can be discarded. It will take at least three years for your new seedlings to mature and develop into a large bush. However, the first bloom will not be seen for one to two years.