How to grow:
Before growing the roses from seed, the seeds have to undergo a period of stratification. This is a cold moist storage that gets the seeds ready for germination.
Cold Treatment
Chilling your seeds in a refrigerator for about six to ten weeks encourages them to germinate faster once planted. However, you must take care to avoid keeping them cold for long as they can germinate while still in the refrigerator. Place your seeds on a paper towel before moistening them. Use half purified water and half peroxide to prevent the growth of mould. You can then place them in a plastic zippered bag, mark the date and variety before placing in a refrigerator set at 1 to 3 degrees C. The paper towel should remain moist for the entire period. You can check occasionally to see if it needs remoistening. Make sure you don’t freeze the towel.
There are other ways to stratify the seeds like planting them in a tray of potting mix 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 for planting (6-10 weeks), remove the bag from the refrigerator if that was your 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 they have good drainage. The ideal size of the trays or pots should be 3-4 inches deep.
You can use separate trays when planting seeds from different varieties of rose hips. You must follow your labeling all the way down from harvesting, treatment, and planting. The rose bush name and planting date are some of the details to indicate on your trays or pots.
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.
Place your seeds about ¼ inch into the soil and dust the surface again to prevent the damp off disease that kills seeds. Water them properly and place them outside in direct sunlight. If there is frost, it is advised you place your seeds under a tree or in a sheltered part of the patio to protect them. There is no need for grow lights.
Keep the soil pots or trays watered but not soggy. Do not let them dry up as this might affect the germination of your seeds.
Watch for germination
After about six weeks, the first two seed leaves will start to emerge before the true leaves can emerge. The seedling must have three to four true leaves before they can be ready for transplanting.
Planting your seedlings
When the seedlings are grown a few inches tall with at least three true leaves, they are ready to be transplanted. You can transplant them into a four-inch pot of your liking. You don’t have to plant all your seedlings but only the healthy ones. You can choose to monitor them on the tray and only transplant them when they have outgrown it.
You must monitor the seedlings as they grow in their new pots for colour, form, bush size, branching, and disease resistance. Roses with weak, unhealthy or unattractive flowers can be discarded. It will take your new seedlings at least three years before they reach maturity and develop into a big bush. However, the first flower can be seen after one or two years.
* Germination rate depends on the country and the weather circumstances.