If you are buying organic Romaine lettuce, celery, or scallions, you have plants!
I just put them in water on the counter until I’m ready to get them in the greenhouse.
I read these will grow with just water, but I add half dirt, then fill with water.
They will go to the garden at some point, but for now, they are happy here in the greenhouse.
I use canning jars, since I won’t be looking for them until the fall anyway.