Woodland flower planting at the beginning the year

Experimental planting is now underway in the wood. The trees are now 9 years old and are really starting to shade out the grass of the field that we planted, and in some areas I used Roundup on the grass last summer. These areas are now bare and have a good covering of leaves. I am not sure whether or not the grass will not regrow in these areas, however I have been planting wild garlic and bluebell bulbs as an experiment to see if they survive. If all goes well I will repeat planting over a much bigger area next winter.