Butterfly bushes (Buddleia or Buddleja) is a genus of flowering shrubs native to Asia, Africa, and the Americas. Once known as an invasive plant, newer varieties are seedless and can safely be grown around the United States. Drier regions like the Southwest can grow all types of butterfly bushes without worry. These plants are very low maintenance once established and can handle periods of extreme heat in the summer and cold in the winter. These bushes can be grown in USDA hardiness zones 5-9. The bushes attract all types of helpful insects including bees, wasps, and of course butterflies.
Be sure to choose a location that gets at least 6 hours of sunlight, preferably 8 or more hours of direct light. The soil needs to drain well, but the plants can handle a wide variety of soil types. Dig a hole twice as wide as the root ball but only about 2 inches deeper. Place the plant at the same level as the dirt around it, and ensure the plant isn't lower than the ground otherwise water will sit on top of the plant and kill it. Once you fill the dirt back in and gently press the dirt down you will need to water at least once per week the first year. After that, the plants should need very little care.
Butterfly bushes are mostly a drought-tolerant shrub. However, during periods of extreme dryness or when the plant is first put into the ground it is necessary to provide additional water. You will be able to tell when the plant needs water by looking at the leaves. If the leaves are starting to wilt or droop, that is a good indication the plant needs more water. The morning is the best time to water the plants, but you can anytime during the day if the plant really needs watered.
Typically butterfly bushes do not need to be fertilized. The plants are vigorous growers without additional fertilizer being added, and it could cause the plant to actually grow too fast or put energy into producing leaves at the expense of flowers. An exception is if the plant is growing in a planter, then fertilizer can be added once per year after the first year of growing. If you do choose to fertilize, the spring is the best time to do so.
Pruning can help ensure the plant keeps a nice shape as well as getting rid of the old dead branches each year. Some of the smaller varieties do not need to be pruned, but you can prune them. The best time to trim is in the spring before the plant begins to form flower buds. The plant grows flowers on new wood each year, so you don't have to worry about cutting off flower buds.
Butterfly bushes do very well growing in pots. This is because of the hardiness of the plant and the extreme conditions the plants can tolerate. Be sure to have the planter in a location that gets at least 6 hours of sunlight per day, if not more. That will ensure the plant blooms as much as possible. The planters will need to have good drainage as well, because the plants can't tolerate soggy roots for long periods of time.
Make sure to protect the plants if temperatures are supposed to drop below 20 degrees fahrenheit with a blanket. Otherwise, the plants are very cold hardy and can tolerate wind and snow very well. The leaves do fall off in the winter, but that isn't a reason to be concerned. You may need to water once per month during long periods of drought during the winter.