my ludwigia repens are growing great. i've have about 8 stems in my tank and trimmed them because they were starting to grow out of the tank. the parts that i trimmed were long enough to re-plant to grow and are doing great. but the place were i trimmed from the original stems aren't growing, they just sprout new branches and are growing out from different places. they are in need of a trim again and i don't want to trim them where they won't grow anymore. also they have little roots growing down from some stem corners, are these ok to trim as well?