Hello there!

The blossom end rot is just because your Dad's plants aren't getting enough calcium. Sometimes this is because the plants haven't had enough water, but most likely not the case with your dad's plants. Since your Dad's soil is quite heavy on the compost, the BER is prob. because the plants have too much nitrogen which causes them to grow faster then they can absorb calcium. I don't really know what you can do about it, other then hope the next peppers that come up are a little healthier.

Plants will wilt in the hot weather to cut down on their water loss to the hot air. It doesn't always mean that they need to be watered. Usually if they are wilting and the ground is still damp I just leave them - they always perk up in the evening, and that way I make sure I don't over water.

Kathryn

Soil is a complex medium made up of different materials of different sizes, and all work together in a particular way to be more than the sum of their parts. That fraction of leaf mold & such has benefits, but soil particles are needed for a number of things, one of them being clay to help the exchange of nutrients. I agree with Kathryn that the mixture is either lacking Ca or isn't of a texture that allows the Ca to be available. You might try to side-dress with Dolomite lime.

Dan

The BER problem may well be caused by the plants not getting sufficient water as Ca and water transport are linked. As an observation, notice perfectly healthy tomato plants with all unblemished fruit. Then, dry out the soil for a couple of days and observe what happens to developing fruit later...BER. I've done it myself unintentionally a time or 2, never fails.

Michael

If the soil is wet then he may be over watering. My plants act a bit droopy when it is particularly hot and sunny outside which for here is high 80s to low 90s. But they perk up after the sun goes down. He only needs to water if he sticks his finger in the soil about an inch or two down and it feels dry. BER can be caused by overwatering too. A good mulch would help maintain the water levels and keep the soil a bit cooler and might help with the drooping.

Also, if the raised part is of a strikingly different composition, the roots may never cross the interface, so he's got what amounts to a long, skinny flowerpot.

I missed what lazygardens caught - nice catch. If the material in the raised part of the row hasn't been incorporated in the native soil, the plant roots may not be going into the native soil as well, making all that unavailable and dependent upon the leaf mold.

Dan

In the fall, I'd maybe work some of that leaf compost down into the native soil, and vice versa.

That daily watering could also be part of the problem, ironically. If the plants always have plenty of water at the surface, they won't have to grow as deep roots trying to get at water that's below, and so they remain dependent on frequent watering.

Another factor might be overcrowding. If the plants are crowded together, that limits the breadth of their root systems. It can also mean that on hot days, there's simply not enough water to go around.

How well does that soil drain, normally?
How long is he watering?
Blossom End Rot is caused by a lack of Calcium, but why that lack has many reasons. Calcium moves slowly from the soil to the plant and needs a large amount of soil moisture to do that. Calcium also moves slowly up the plants vascular system and needs lots of moisture to do that. If the soil is not moist enough that may indicate that not enough water is being applied each time.