Hello Barbara: I believe you are describing False Nettle (Boehmeria cylindrica). False Nettle likes moist soils and with the amount of rainfall we have seen throughout the state, it is likely that seeds that have been dormant for some time, had the right conditions to germinate and grow. It is a native plant and is actually sought out by gardeners looking to naturalize.
It will flower and set seed over a period of several weeks. One management strategy since it is a herbaceous perennial is to not allow the plant to go to seed to reduce future populations and then to dig/pull or treat the remaining plants. You may need to use 2 or 3 treatments of your systemic herbicide and at the maximum rate allowed. Late Summer and Early Fall are better treatment times.
Sincerely, Richard
