Deiselrider first I want to say that I would only do this for 1st and 2nd year plants,that I had record of to be sure they where that young is important,because older will live..
3ed year will stay no matter the varment problim,even if the leaves are eaten,becaue the root will not pull from the ground.
If the problim is deer I would top the plants as soon as the leaves begin to unfold(around spring turkey season,or Easter)because they will pull the root out as they eat the top,especialy deer,because they pull every thing they eat,instead of just chewing or biteing it off,they pull as they bite....although I truly love to hunt deer that can be a problim with them in the seng area.
Around here we do not have that problim,the deer have a vast supply of food,and dont eat alot of the seng,as I posted in another topic.I have found seng around bedding areas localy,but have had sevral friends a few countys away complain aout this same matter,
Billy.