When raspberries vines begin growing in the spring, they propagate by shooting up runners from their root systems. These runners will fruit bear next year's raspberries. If a raspberry patch has become overburdened with excessive runners, you can dig these up and plant them elsewhere. Removing the runners helps keep the existing vines healthy because they get more light, water and airflow. A raspberry runner has tiny fibrous roots which feed the plant after transplanting. New plants grown in the spring and you should transplant during this rapid growth period.
Locate the new runners next to the parent plant. These will be tender shoots with green stems.
Dig the earth away from the runner with a garden trowel and follow it back toward the parent plant's roots. Sever the runner from the parent rootstock with as many of the small fibrous roots intact as possible. Cut the runner with a pair of pruning loppers.
Place the runner in a pot full of well-draining soil high in organic matter. Bury all of the root system of the runner 2 inches below the surface and press the soil in around the its base. Keep the soil wet until the runner has established its root system. Protect the transplant from winds which could knock it over by placing it in a wind-protected corner.
Dig a hole in an area of the garden with ample sunlight, well-draining soil and high organic matter content. Use a garden trowel to dig the hole. The hole needs to be deep enough to accommodate the soil in the pot and the runner. Remove the established runner from the pot along with the dirt it's in and plant it in the hole. Keep it wet until the soil settles and then only water 1 inch per week throughout the growing season.
Test the planting area for loaminess by setting up a sprinkler and watching to see how long it take the soil to drain. If you notice a lot of puddling, you may need to amend the area with sand or perlite.
Failure to get as much of the root as possible may result in death to the runner.