The flowers in the street market appear with the daylight, at Marché Maubert, on Tuesdays, Thursdays, and Saturdays. Most of the vendors display their wares at Marché Monge on the other days of the week. Both of these markets have a flavor of the neighborhoods, and I have stayed just around the corner of Marché Maubert on many visits to Paris.
If you return late in the day, you would not even imagine that there had been a street market only a few hours earlier. The vendors fold up their tents for another day. The city of Paris supplies and installs the poles and supports for this market at Place Maubert and at other market sites around the city.