Butterfly bush (Buddleia davidii) is a deciduous, fast growing shrub that can grow as much as 8 feet in one season. The butterfly bush produces cone-shaped blooms in red, pink, white or purple. The blooms, which attract butterflies and bees, can cause the stems to droop. The butterfly bush is cold hardy in USDA zones 5 to 9 and can be propagated from stem cuttings.
Prepare the planting medium, which may be coarse sand or equal parts sand and peat moss. Place the planting medium in a pot. Water the planting medium until water comes out the drain holes.
Clean the garden clippers with rubbing alcohol or a 1:9 solution of bleach to water, which is roughly 2 tbsp. bleach to 1 cup water.
Gather cuttings from the butterfly bush. Make a straight cut about 8 inches down from the tip of a healthy stem that has no buds.
Snip off the leaves on the bottom 1/3 of the cuttings.
Transfer a small amount (about 1/2 tsp.) rooting hormone to another container, like a saucer or sandwich bag. Dip or roll the bottom 1/3 of the cutting in the rooting hormone. Throw out any leftover rooting hormone.
Poke a hole in the planting medium as deep as 1/3 of the cutting. Use your finger or a pencil. Place the cutting in the hole. Lightly water around the cutting to get the soil to settle so the cutting will stand up. If you are growing more than one cutting, place them 2 inches apart in the pot.
Cover the cutting and pot rim with plastic that does not touch the cutting. A large twist-tie food storage bag is stiff enough to remain upright. Allow one corner of the bag to hover over the cutting and then pull the rest of the bag tight around the pot. Use the twist-tie or a rubber band to hold the bag in place.
Place the pot in indirect sunlight. Keep the soil moist; there should always be moisture inside the bag. When new growth cramps the cutting against the top of the bag, which may take several months, remove the bag.
Leave the cutting in the pot until the following spring. The cutting can be planted outdoors in late spring.