After the stretching, it turned out I had to get a bigger tent! Three plants will *not* thrive in a 2x2x5! Everyone's now much happier in a 3x3x6 (that is 80x80x80 in centimeters), not only in terms of canopy surface but also in terms of height (they were getting dangerously close to the lights in the previous tent). As expected, temperature and humidity control is also easier in a larger tent.