Actually. to act as "nurseries" you want the needles on for the densest cover possible . (btw, DO NOT ever try to `flash burn` the needles off; it`s like trying to burn off a single cup off of a whole gallon of gasoline; it just "DON`T" work very well- been there, tried that...) Sink with needles on. The needles will naturally fall off in about 8 months. The 2cnd year underwater is when the trees will best produce...most "C" trees will last between 4-6 yrs or more depending on the type of tree (cedars last longest followed by spruces), type of body of water, how deep they are placed, and how they are rigged...good luck sir and make us proud ! You too will learn the POWER of the "C" tree...