Some of them should pull out easily but you can also try burying them under additional layers of lasagna bed ingredients. It works just like any mulch - make the layers thick enough to block the light - no light no germination.

Dave

Very often the straw will still have seeds, the grain, that the straw grew and people often see that as "weeds" when it is simply the oats, wheat, barley, etc. that the straw grew. They are not a problem and are a sort of green manure. Nothing needs to be done because this grass like growth will die off on its own when the seed heads ripen.

Probably what you DON'T want to do is use a *thin* layer of straw. Doing so will add weed seeds, but the straw mulch will not be thick enough to smother them. If you use a thick enough layer, then yes, you'll still get some weed seedlings from the parent straw material, but they will have a very shallow root and will be very easy to pull out with just a gentle tug. I don't even remove them - just tug them until I can feel the root pop out of the soil, then leave them there to become part of the mulch.

-Diggity