Plant shadows can be individual to each plant, or can be connected to the document…
Vectorworks Tip #251 – Plants – Creating Custom Plant Classes
Intermediate Tip – As well as the default classes for your plants, you can also create your own classes to control parts of the plants. In this image, you can see several other classes that deal with plants but are not the default classes. I use these classes to control the visibility of my plants, allowing me to create concept drawings and construction drawings from the same plant by changing the class settings in the viewpoints. This saves me a lot of time redrawing plans.