Okay, I put round up in my gardening area. A day later I put Preen® in my flower bed. I was planning on planting my flowers on Saturday, would that be safe? Or would it kill my flowers? (They are over 3in tall). I read on the container for the Preen® it is harmful to skin. There is still little pebbles from the Preen in my flower bed, would they be gone by Saturday? (I put Round Up on on Apirl 14th and I put Preen on on April 15th).
Round-up is a "contact killer". In other words, it only kills what ever it comes in contact with the leaves of so to speak. Once it's washed down in the ground it does nothing which is why you can spray it around trees for weeds and not hurt the tree (unless it's on the leaves of the tree) The Preen, I'm not sure about.