Jane et al., The only counter-argument to leaving old tunics in place would be where there is danger of pests such as mealy bugs or diseases such as pathological rots that might be harbored in the old tunics. Otherwise, I go with Arnold: If nature leaves them, so can we. As for actual data, no, I've never seen even a whiff of data on the subject. Jim Shields ************************************************* Jim Shields USDA Zone 5 Shields Gardens, Ltd. P.O. Box 92 WWW: http://www.shieldsgardens.com/ Westfield, Indiana 46074, USA Tel. ++1-317-867-3344 or toll-free 1-866-449-3344 in USA