I know it sounds like no advice at all, but you should strive to keep them 'just right' when it comes to moisture levels. The problem with that lies in the fact that trying to keep moisture levels 'ideal' in water-retentive soils leads to salt build-up in the soil. If you shoot for a fast draining soil mix that still has good water retention, you can almost forget about the over-watering issues, as long as you're willing to water a little more often than what you might be used to.

The high soil temperatures, wet and/or dry soil conditions, lack of Ca in the soil, low pH, and an unbalance in nutrients, particularly Mg, are all things to guard against to prevent BER.

Al

Thanks for the reply.

Given the heat should I err on the moist or dry side? In the greenhouse the transition from moist to dry seemed abrupt. The soil would seem moist; but, it would be dry in the afternoon.

If you are having heat issues, I would opt for a growing medium that was porous enough to allow you to water daily or more frequently if you chose to with no risk of root rot.

Assuming you are watering with cool water, it can drop the temperatures inside the container significantly.

Whether the medium be on the moist or dry side the heat still builds up in the air spaces so a watering just before mid day can help in preventing the temps inside the container from going through the roof.