While watering in the evening (late evening, when the sun is setting) isn’t the best since that’s when the slugs come out, it cools the soil down and gives tender greens a much-needed reprieve. Warm-loving plants like tomatoes, on the other hand, get watered in the early morning. They enjoy the warm soil and high nighttime temperatures.
You can give your greens a rest by sheltering them a bit with some shade cloth. Floating row cover (a.k.a remay), the white flowy garden fabric that looks like interfacing, can be placed over the cloche hoops that normally hold plastic. The row cover lets filtered sun light in as well as moisture when it rains. And remember, containers dry out quickly! Greens sown in pots may need a drink sooner than those sown in a raised bed. A little warm weather vigilance goes a long way.