Rhododendron is a genus that contains over 1000 species of flowering plants, some of which are native to the United States. Its use in the residential landscape is varied, from specimen plantings to hedging. Known as "acid-loving" plants, rhododendrons require a soil pH of 4.5 to 5.5. Once the proper pH is obtained, the rhododendron is an easy plant to grow and provides masses of colorful flowers in the garden. Take the rhododendron cuttings in September or October.
Water your rhododendron bush until the water puddles at the base on the day before you plan to take the cuttings.
Choose stems from the rhododendron. You can root 12 cuttings (6 inches each) in each 6-inch pot. The experts at the American Rhododendron Society recommend that you choose branches that are growing straight up, rather than from the side of the plant. They also suggest that you choose pliable growth from the current year: you should be able to bend the cutting without breaking it.
Use a sharp knife or razor blade to cut the branches from the shrub. Place them in a plastic bag, out of direct sunlight, until you are ready to plant them.
Mix together equal parts of sphagnum peat and perlite, and moisten well. You may have to stir the mixture as you add water to ensure that it is uniformly moist.
Pour the planting mix into the planting pot to within 1-inch of the rim and pack it firmly. Use your finger or a pencil to create deep, narrow holes in the soil for the cuttings.
Remove all the leaves from the cuttings, with the exception of three or four at the top.
Cut the stem, at an angle, immediately below a leaf node (swollen area on the stem where a leaf was attached). Do this for each cutting that you will be planting. Dip this end of the cuttings into rooting hormone.
Stick the cuttings into the prepared holes and pack the soil around them. Water the cuttings until the water drains from the bottom of the pot. Allow the soil to drain completely.
Place the pot in the plastic bag and secure the top with the twist tie. Place a rubber band around the rim of the pot. The specialists at the American Rhododendron Society say that the rubber band will prevent water from dripping down the side of the bag and pot.
Place the potted cuttings in an area with lots of light (no direct sun) that remains at least 70 degrees Fahrenheit. If using grow lights, place the light 1 foot above the pot.
Check the cutting periodically for signs of soil fungus. Use a fungicide, according to package directions, should any appear. Remove any cuttings that have died. The rhododendron cuttings will take three to four months to root.
Transplant the cuttings into individual pots using the same peat/perlite mixture. Water the cuttings with 10-10-10 fertilizer, diluted to one-fourth the strength recommended on the package, then place the pots in plastic bags with the top left open. Transplant the rhododendrons into their permanent location when the weather warms to over 70 degrees.