Butterfly bushes

Asked August 12, 2020, 1:50 PM EDT

My neighbors butterfly bushes have well over grown my property. I've been cutting them back for years. How big does a butterfly bush grow every month?

Lane County Oregon

1 Response

Butterfly Bush is extremely successful at reproduction, giving it a competitive advantage over native flowering shrubs. It excels at seed production and dispersal. A study at Longwood Gardens found that there were over 40,000 seeds on a single flower spike. The shrub reaches maturity quite quickly, often producing extremely lightweight, winged seeds within the first year of growth, which travel far distances by way of water or wind. The germination rate is about 80 percent or above. These seeds can remain viable for three to five years in soil, and any cut stems can sprout again. It is classed as an invasive plant in Oregon and is not supposed to be sold any more. It is important that anyone growing this cut off all flower heads before they can set seed!
Butterfly Bush is extremely successful at reproduction, giving it a competitive advantage over native flowering shrubs. It excels at seed production and dispersal. A study at Longwood Gardens found that there were over 40,000 seeds on a single flower spike. The shrub reaches maturity quite quickly, often producing extremely lightweight, winged seeds within the first year of growth, which travel far distances by way of water or wind. The germination rate is about 80 percent or above. These seeds can remain viable for three to five years in soil, and any cut stems can sprout again.
Butterfly Bush can be difficult to manage once it has been established. Seedlings can be manually removed. It is possible to uproot and dig out mature specimens. The roots must be removed or they will re-sprout. Areas around the removal site should be planted with a native ground cover to prevent future seedling germination. You must dispose of any plant material completely, by burning or putting out in the garbage. Branches left on the ground can root into new shrubs.
Perhaps you can discuss with your neighbor the possibility of flower removal before seed set. Such flowers need to go into the garbage as otherwise they might still set seeds. The seeds can stay in the soil for quite a while, so keep a sharp eye out for new seedlings. If there are currently none growing on your property, then it is a matter of keeping up the pruning and allowing no flowers. The bush can easily grow to 8x8 or even as much as 15' high. I hope this helps you some.