Water your viburnum the day before you take cuttings to ensure that it is well hydrated. Make sure the plant is healthy.
Take softwood cuttings from the viburnum in the morning, when the plant is still hydrated. Before you begin, wipe your cutting tool, either a sharp knife or garden pruners, with rubbing alcohol to prevent the spread of bacteria or fungus to the softwood cuttings.
Fill several 3-inch plastic pots with a sterile potting medium, such as half perlite and half peat moss. Don't use garden soil, which will be too heavy, and can carry pests and disease. Be sure the plastic pots have drainage holes in the bottom, as excessively moist soil will rot the cuttings. Spray the potting mixture with water until the soil is damp clear through, then set the pots aside until you're ready to plant cuttings in them.
Choose a shoot that snaps easily when you bend it. If the shoot bends but doesn't snap, the shoot is too new. If the shoot is so woody that it won't easily bend, it's too mature. Take several cuttings, because chances are good that not all of them will successfully root. Shoots taken from the upper part of the plant are younger, and will usually be easier to root.
Cut a stem with 4 to 6 sets of leaves. A suitable stem will be 4 to 6 inches long. Make the cut at a slight slant, just below a leaf. Strip the leaves from the lower half of the viburnum stem cutting.
Dip the cut end of each stem in powdered rooting hormone, and plant the cuttings in the pots, with the leaves not touching the soil. Spray the pots lightly with water to settle the potting mixture around the cuttings.
Slide each pot into a zip-lock bag, and seal the bag securely. If necessary, place small stakes in the pots to keep the plastic from touching the viburnum leaves or the potting mixture.
Place the pots in a bright spot, in indirect light. Avoid direct sunlight or a sunny window, as the heat will magnify inside the plastic and will bake the viburnum cuttings. Check the bag daily. If there is no visible condensation on the inside of the bag, open the bag and mist the potting mixture.
Watch for the viburnum stem cuttings to root in 4 to 6 weeks. To determine if the cuttings have rooted, dig up one cutting carefully with a spoon, check the roots, and re-plant the cutting. Once the roots are a minimum of an inch long, open the top of the bag for a few days so the viburnum cuttings can acclimate to a drier, cooler environment, then remove the pots from the plastic.
Plant each cutting in a one-gallon container filled with commercial potting mixture. Place the viburnum cuttings in bright sunlight, and keep the soil moist.
In late summer, bury the gallon containers in the soil where the viburnum will be sheltered from cold wind. Bury the containers up to the top, and mulch around the containers to protect the viburnum from freezing temperatures. Allow the viburnum to mature for about a year, then plant them in a permanent location.