The experiment: wrap-up
The cress sprouted and grew so quickly, I could not even get around to writing about it in time. So here is a wrap-up. First and most importantly: the experiment worked out. This also means that (at least at the beginning) coffee grounds do no harm to garden cress. The pictures were taken on day 2, day 4, day 5, and day 6. Now it only remains to cut it and to eat it.