Butterfly bushes are one of those plants that straddle the line between a shrub and a perennial. They are very fast growing in the right conditions, and bloom on new growth that season. That means that they can be cut back almost to the ground every year without worrying about messing with flower production.
They are wonderful, easy to grow plants, especially if you give them a little maintenance this time of year.
Late winter to early spring is the time to prune them, before they leaf out for the season. If it was just planted, cut it back by about half its size or so, but if it’s established in its spot for a couple years or more, go ahead and go all the way to a few inches off the ground. This will help revitalize it for the season and keep its size in check.
Below is one of those poor specimens that we’ve probably all seen. It’s been planted in a spot with too much shade and hasn’t been pruned heavily enough over the years. This creates a straggly, woody looking plant that is prone to splitting. If you have one that looks like that, try cutting it all the way to the ground and see how it does for you. If it comes back very spindly chances are that it’s not getting enough sun.
Here are a few more tips for growing these fantastic plants:
- They like a little more alkaline soil than what most of us have around Asheville, so when you trim them it’s a good idea to top dress with a little pelletized lime every other year or so. Lime is also known as poor man’s fertilizer.
- If you have one of the more leggy old fashioned varieties like Black Knight, try putting multiple colors close together. When they bloom, they will twine together and create a neat bicolor effect that looks like it’s all from the same shrub. That could be done as a hedge as well.
- Choose wisely, they can be quite different in habit. The newer varieties can be much fuller and shorter plants. Check out the Monarch collection or many of the Proven Winners options if you are looking for a more compact variety.
- Deadhead. All that crazy growth does take a little work to maintain. If you cut off spent blooms it dramatically extends the bloom time and keeps the plant tidier, especially the older varieties.
- Topdress in the spring with fertilizer. Fast growth means hungry plants. If you like things low maintenance, go with a slow release fertilizer like Ozmocote 14 14 14.
- Try a white one! White flowering shrubs like butterfly bush or paniculata hydrangeas can create a dramatic backdrop for summer blooming perennials like echinacea.
- Full sun is the way to go for the best blooms and habit.
- Don’t cut it back in the fall, especially around Asheville when the weather jumps from freezing to 70 degrees in the same week. Wait until late winter when you can be sure that it’s dormant.
Butterfly bushes are adaptable, easy to grow plants that do best in full sun with well draining soil and lots of nitrogen. Give them a massive haircut each year from late winter to spring to keep them looking their best.