Benefits of Crown division
Rhodiola can be propagated from seed, or through crown division or bud cuttings. Plants reproduced by division or cuttings establish more rapidly and are initially more vigorous than those grown from seedlings. By using cuttings over seeds, the farmer may be able to harvest in four years or less. In addition, the farmer can forego all the work of seed germination and care of seedlings.
These types of vegetative propagation also produce plants that are genetically the same as the parent.
Taking Bud Cuttings
Newly developing buds that are removed from a growing plant will root readily. The mother plant regenerates and produces new buds. The ideal time to try rooting buds is in the spring before the buds have turned green and have leaves.
Bud cuttings can be transplanted into moist soil in individual pots and placed in light shade in a cold frame or greenhouse until well-rooted. It is not known if rooting hormone will improve the survival of bud cuttings.
Crown or Root Division
For any root division to survive, it will need to have at least one bud and some portion of the crown and/or roots. The roots are cut into sections 1 to 6 inches long, with at least one bud on each division. Crown division can be performed in early spring on crops in their third year or older. The buds should be growing, but not green and shooting. The optimal bud size is .25 to 3.0 inches long.
Remove the plant from the ground and take away all weeds and dirt by brushing or knocking the root on a hard surface. Do not bruise or crush the root. With both hands break the root at its natural break points or where it will easily break. For more divisions, these pieces can be split apart with a knife, making sure to include at least one bud and some crown or root.
Expose the pieces to air for 1 to 2 days before planting. This will allow the broken surfaces to heal and prevent take up of soil-borne diseases.
Soak pieces for 30 minutes in 10-52-10 liquid fertilizer just prior to transplanting. Transplant directly into the field as per your field design and spacing. Water heavily after transplanting.
This is the recommended method of propagation for large-scale operations with ample root stock. Growers report this method should provide 90% success rate with strains of Rhodiola rosea which are robust in your area.