Pat, I gather Horseweed at the end of growing season, still a little green but dry out strong and wall thickness is at its peak , like you said deteriorates after winter moisture arrives. Horseweed is perfect for handdrills . Long, straight, tuff and have a pithy center for easy dust and easy ignition to a coal on a pc of white pine hearth board. Seem to have also made the Ready Round up jump where it will not kill it, I see lots of Horseweed in the Soybean fields late in the season. Bob