There are two ways to add plants to your plans. The first (and easiest) way…
Vectorworks Tip #235 – Plant Tool – Placing Plants in a Triangular Array
Use this mode when you want to place multiple plants in a triangular array Vectorworks will use the plant size and spacing from the plant definition, and the plants will be placed orthogonally on the screen. Use the rotate plan tool to rotate the plan to suit the site boundary if you need to.