Caryopteris can spread, but it depends on the specific variety and growing conditions. In my personal experience, I have seen Caryopteris spread slowly through underground runners, sending up new shoots a few feet away from the original plant. However, it is not an aggressive spreader like some other plants.
The spread of Caryopteris can be controlled through regular pruning and maintenance. By cutting back the plant in early spring before it starts to grow and leaf out, you can keep it in check and prevent it from spreading too much. Pruning also helps to maintain a compact and bushy shape.
It’s important to note that Caryopteris blooms on new wood, which means that the flowers appear on the current year’s growth. So, pruning it back in early spring not only helps with controlling its spread but also encourages the growth of new branches and more flowers.
In terms of growing conditions, Caryopteris prefers well-draining soil and full sun exposure. It is drought-tolerant once established and generally low-maintenance. However, it may benefit from some occasional watering during dry spells. Providing the plant with proper care and optimal growing conditions can help to keep its spread in check.
To summarize, Caryopteris can spread slowly through underground runners, but it is not an aggressive or invasive plant. Regular pruning and maintenance can help control its spread, and providing optimal growing conditions will contribute to its overall health and appearance.