Time Frame

• Take a root cutting from the mother plant in late winter before new leaves emerge. Cuttings taken while the plant is dormant root better and cause less damage to the existing plant. Take root cuttings from hydrangeas that are at least two to three years old. Younger plants won't have large enough roots for successful propagation.
  
  

Indoor Growth

• To propagate hydrangeas indoors from root cuttings, take 2 to 6-inch cuttings from the existing plant's roots. Press the soil evenly around the hydrangea's roots after taking the cuttings to avoid damage. Place the root cuttings horizontally in a tray containing coarse sand or vermiculite. Cover the roots with 1/2 inch of sand or vermiculite and mist with a spray bottle filled with water to keep it evenly moist. Check the root cutting in three to four weeks for fine new rootlets. Plant the cutting in a pot with potting soil once new roots have formed.
  
  

Outdoor Growth

• Take 2 to 6-inch-long cuttings from the hydrangea plant. Snip the ends that were attached to the mother plant with a straight cut. Make a slanted cut on the opposite ends. Store the cuttings for three weeks in moistened sawdust, coarse sand or vermiculite in the refrigerator. Plant the cuttings in moist, well-drained soil outdoors in spring. Space the cuttings 2 to 3 inches apart and plant them so the end with the straight cut is buried 2 to 3 inches below the surface.
  
  

Considerations

• Hydrangeas grown from root cuttings take several years to mature and blossom. The other disadvantage to root cutting is that only a few cuttings can be taken without damaging the plant. The cuttings root best when they are at least 1/4 to 1/2 inch in diameter. Take stem cuttings or use layering to propagate more hydrangeas.