Rhubarb is normally propagated by planting “sets”, each of them consisting of a fleshy rootstock with at least one healthy but, but preferably is 4 or 5 for best results. Sets should have about 10 cm in diameter.
You can separate sets from a healthy 2 or 3 years old plant by lifting the plant and slicing through the crown. Replant the parent plant.
On light soils, plant the sets so that 2,5 cm of soil cover the buds. On heavy or wet soils, plant with buds just above ground level. Leave a space between plants of 90 cm as a mature plant will need like a square meter to develop well. Protect the new plant from the winter frosts by covering them with dry straw.
Rhubarb may also be raised from seeds sowed in spring, 2,5 cm deep in rows 30 cm apart, in a sheltered outdoors, but the result is not the most satisfying because will take like 3 to 4 years until the first real harvest is possible.