Q: Help! I need to get rid of some St. John’s Wort that has come up on a large portion of my lawn. This section actually used to be a vegetable garden that I let go back into grass. I would like to turn it back into a garden, but it doesn't seem to matter how deep I dig, I can’t get all the roots of the St. John’s Wort.
St. John’s Wort (Hypericum calycinum) is a perennial and mainly spreads itself by way of root systems. I would suggest combining two methods. First, mow the area as close as possible. Next, mulch the area with coarse wood chips, similar in texture to a tree that has been put through a wood chipper. Ensure the layer of mulch is 15- to 20-cm-deep (6- to 8-in.) and maintained year round. Cut back any emerging shoots with a weed trimmer. Be patient and persistent as you slowly suffocate and weaken the plant roots over time (remember the plant did not occur there overnight).