Trifluralin is a root inhibitor that is incorporated into (binds with) soil. I imagine binding turns it into a slow release treatment that doesn't stand much chance of damaging established roots but is very damaging for roots of newly sprouting plants. Transplants need to reestablish feeder roots to successfully merge with their new home...and trifluralin would inhibit that feeder root growth, too. Apply it after you've planted a bed and it doesn't get a chance to bind with soil first -- it might even be absorbed by transplant roots in concentrations that are strong enough to cause damage to delicate transplant roots...even if they aren't feeder roots...which would be even more of a setback than transplant shock delivers. http://www.preen.com/faqs/answers.asp If you over apply Preen and need to neutralize what's there: Apply activated charcoal at the rate of 1lb. per 100 sq.ft. Lightly work into surface of soil. Water each day for 3 days. It should be neutralized two days after that. http://pmep.cce.cornell.edu/profiles/extoxnet/pyrethrins-ziram/triflural in-ext.html http://pmep.cce.cornell.edu/profiles/extoxnet/index.html Barb in Southern Indiana Zone 5/6 dorsettm@scin.quik.com A root is a flower that disdains fame. > Can't be used after transplant, can be used up to 10 weeks > prior to planting > up to 1 day prior to transplanting. So what's the difference > between 1 day > prior to transplant and after transplant? It isn't going to > dissipate in 24 > hours. > > My son used this product last year 2 or 3 times in his > vegetable garden after > the plants were established. He grows squash, beans, chiles, > tomatoes, etc. > He had a huge harvest. > > Now what is the deal on this stuff? > > What is it really and will it harm my plants? > > It doesn't hurt bees. > > Mary-Anne >