weeds in mondo

Could you please tell us what mondo are? Not familiar with them over here.

Mondo is an ormantial grass. It is sometimes called "monkey grass". It comes in several varities, but mine is the dwaft. thanks

Well, if it in clumps with the weeds growing amongst the grasses, the only way really, unfortunately, is to dig up a clump at a time, clean out the weeds and ensure that the soil is also weed-free, then re-plant your grasses. Obviously weed killer is not feasible, and I am assuming that you can't hand-weed the plot with the grasses 'in situ'? Long tedious job, but I can't think of any other way to get rid of the weeds completely.