Viburnum shrubs propagate readily from stem cuttings. It’s possible to grow them from hardwood cuttings taken from a shrub during its dormancy in the winter. However, you’ll probably obtain better results with softwood cuttings taken during the active growing season. These are much more reliable and tend to root quicker. They’ll develop into healthy, growing plants in a much shorter time. It’s best to do this early in the morning, from late May through July.
Choose an attractive, healthy viburnum shrub to take your cutting from. Select a softwood stem with at least two sets of leaves on it from this year’s growth. Test the stem’s suitability as a cutting. If it bends easily and breaks with a crisp snap, it’s ready. Use clean, sharp shears to trim a 4-to-6-inch cutting from the mother plant, and keep it cool and moist until you’re ready to plant it.
Make a rooting medium by combining 60 percent perlite and 40 percent peat moss. Fill a 3-inch pot with the mix, and set it in a shallow container of water until the surface feels moist to the touch. Take the pot out of the water, and let it drain for a couple of hours.
Remove all the leaves from the lower half of the viburnum cutting. Dampen the bottom one-third of the stem with water, and dip it in powdered rooting hormone. Poke a hole in the middle of the rooting medium, and plant the treated portion of the stem in it. Cover the cutting with a plastic sandwich bag to retain humidity.
Set the cutting in a warm, brightly lit spot out of direct sun. The top of a refrigerator or above a hot water heater are ideal locations.
Water the viburnum cutting just enough to keep the rooting medium evenly moist but not soggy or wet. It shouldn’t be allowed to dry out. Mist the cutting when you water. The plant should root in about 4 to 6 weeks.
Check for root development in about 4 weeks. Tug the cutting gently upward. If it resists, it is rooting satisfactorily. You can remove the plastic bag and transplant the cutting. If it pulls out of the medium easily, inspect it closely to see if tiny root hairs have emerged. If they have, replant it and check again in 2 or 3 weeks. If no root development is apparent, toss the cutting and try again.
Combine 80 percent all-purpose potting soil and 20 percent perlite, and transplant the rooted cutting into a 6-inch pot. Water enough to evenly moisten the soil. Feed the young viburnum a liquid seaweed fertilizer according to the packaging instructions. Place it in the sunshine in your garden.