Shiso was banished from my garden this week. In early spring, I obtained a package of shiso seeds, both green and red (Perilla frutescens var. crispa). They were from a reputable company; the package itself was pretty and full of information. Although they were difficult to germinate I had about four small plants, three with red leaves and one with green leaves growing in my bean/cucumber bed by the beginning of June. Similar to coleus, shiso is a warm weather annual used quite a bit in Asian cooking. I was looking forward to learning how to use them, I was already thinking of putting the leaves in a green salad and brewing a shiso tea.
Last night, my daughter and I went for walk and I noticed that a neighbor had quite a lot of red shiso in her front yard, several feet high. Further down, more shiso plants were visible but in cracks in the sidewalk — wherever it could get toehold in some soil. I have never seen such an aggressive edible plant before (except for mint) so I looked up shiso on the internet. Turns out shiso is a cousin of mint but spreads via seeds while mint runs along its stems and sets roots. According to the Virginia Native Plant Society, shiso is on the September 2009 Invasive Alien Plant Species of Virginia list as “occasionally invasive.” According to the National Park Service, “it readily escapes cultivation and has become a problematic invasive plant in natural areas across the mid Atlantic region.” Shiso is toxic to herbivores including cattle and NPS recommends not purchasing or planting shiso. I have battled Korean bellflower (Campanula takesimana) for years and have no wish to repeat that performance so I have no qualms about pulling a few plants. However, I find it fascinating that this invasive quality was never mentioned on the seed packet. Maybe it is not a problem in other areas of this country but if I had not taken that walk, I would have never known shiso’s dark side until it was too late. Most likely, I would have let one of my plants go to seed and would have been pulling shiso out of my garden for years to come, just like the Korean bellflower. Well I’m on to you, shiso, sorry, not my garden.