I've got a customer that wants us to install dragons blood in between some stepping stones and let it grow in around all of the stones. The problem is that she has a weed problem in the area and will be fighting the weeds until all the dragon's blood is grown in. Her idea was to put landscaping cloth underneath the whole area and plant the dragons blood and let it grow over the cloth. However, I told her I did not think that would work because the dragon's blood will not have a way to develop a root system in the areas it tries to move to because of the cloth. So, I told her that maybe what I could do is pull the weeds or use a trimmer to get them out and she could use some type of pre-em on the area. I figure that the dragon's blood won't have any trouble creeping when a pre-em is applied because it is already germinated. What type of pre-em could I use that won't be harmful to her grandkids or dogs? I was thinking maybe to have her put down some preen after I'm done. Will a pre-em hinder the spread of the dragon's blood? Was I wrong about the landscaping cloth idea? Should she just water it a ton and get that stuff to grow in quickly so that it will choke out any weeds?