I am sorry for this delayed reply to your gardening question. The spring rush has brought a deluge of questions and we are working hard to catch up!
Nutgrass is indeed a terrible weed. One option for your situation is to use a wiper type applicator to apply glyphosate (Roundup is one brand) to the nutgrass plants as they emerge. This will need to be an ongoing battle but in time would be pretty successful if you stay diligent all through the growing season and not give it a chance to recover even for a brief time.
You might want to contact your County Extension Office for other suggestions and product options.
Thanks for the question. Please stop in again soon!
Q&A Library Searching Tips