I spend time every day once pods start appearing cutting off every pod I don't want I can find - the volunteers show up in the area where I was growing 15 different cultivars in three large containers because I obviously missed some. No matter how vigilant I am I always get volunteers .. since I hit them all with weed killer when they start to show, I've never had any "get away" from me in the last 10 years. Also, now that I've changed the way I grow them using the masonry ladders it will be easier to keep track of them.
