When plant species are aggressive — but not technically invasive, according to state guidelines — gardeners may have more complicated choices ahead of them. Massachusetts bans more than 140 ...

Some plants also release chemicals or have aggressive root systems that can harm neighboring plants. Understanding which plants to keep apart is essential for a thriving and harmonious garden.

Armed with suction cup-like puncturing roots, it clings to other plants and can constrict small shrubs and less aggressive species," Melvin explained. With its drooping clusters of purple flowers ...