Yes, you can leave the foliage on your uprooted daffodils. This will help them form next year's flowers so they may bloom again next spring if you plant them back into the garden in the fall. Try to keep the leaves green for as long as possible by placing the bulbs into bins of soil and watering them. When the leaves are all brown store the bulbs without the foliage in a dry spot. A humid greenhouse would not be good but a dry greenhouse would be fine if the bulbs are hidden from the sunlight under the benches or covered with a box. The bulbs do not need to be cool but not over 80 degrees and they must stay dry. Good luck - I see daffodils blooming in your garden next spring. Keep growing, Marianne Binetti