Hi all
I have always used roundup to clean the daffodils beds, in the summer months I clean them with switch hoe ( bit like a Dutch hoe but only one side connected to the shaft and the blade cuts both ways) then I spray. The same method as Clay. I also spray about late October early November after the bulbs have been planted, to clean the beds and paths of newly grown weeds. It may take a little longer for the roundup to work at this time of the year because of the cooler temperature, but it does. I have never lost a bulb through roundup, because it never touches the bulb or its foliage and is bio-degradable in the soil.
Roger Braithwaite