Raspberries (Rubus idaeus) require a climate offering moist, somewhat cool conditions. Gardeners can successfully grow plants at home using fresh seeds.
Fill a 2-inch-deep nursery tray with sterile, low-nutrient seed-starting compost. Spray the compost liberally with a water-filled spray bottle until it feels moist throughout.
Space the raspberry seeds 1 inch apart on the surface of the seed-starting compost. Press the seeds firmly onto the surface of the compost with your palm. Cover them with a very thin layer of medium-grit sand.
Place the nursery tray outdoors in a ventilated cold frame that stands against a shaded, north-facing wall. Leave the tray under those conditions for the winter months to cold stratify, which will break the seeds' dormancy.
Maintain light moisture in the seed-starting compost with the water-filled spray bottle. Avoid letting the compost dry out for longer than a few hours since very dry conditions sometimes cause raspberry seeds to go dormant again.
Remove the nursery tray from the cold frame in spring once daytime temperatures reach 60 F. Place it on a garden bench under light, dappled shade. Continue to water whenever the compost feels dry.
Watch for germination four to six weeks after removing the nursery tray from the cold frame. Transplant the raspberry seedlings into individual 4-inch pots filled with potting soil once they grow to 1 inch in height and produce a set of mature leaves.
Grow the young raspberry plants under dappled shade for their first summer and in the ventilated cold frame over the winter. Transplant them into a sunny or partially shaded bed with mildly acidic, draining soil the following spring after soil temperatures warm to 60 F.