There's so many variables here:

Potting media
Fertilizer
Watering regimen
Climate (Temps & Humidity)
Etc.

Start by adding your Your Plant Hardiness Zone to your profile so we know where you're located!

I'll try to answer as best I can. I use miracle gro potting mix for all my peppers, no reason for me to change since my plants do great each year. I fertilize with Dr. Earth 4-6-2 tomato and vegetable fertilizer once every two weeks. My watering regimen is to wait until my plants are beginning to look like they are melting and then they are given a heavy watering. In northern Virginia the summers are absurdly hot and humid. I am following the same procedure I have had success with in the past. It just seemed strange to me that these plants were not even attempting to produce buds.

I live in near the same zone but over in PA and my peppers one super hot and a chocolate habanero are not doing so hot they started about a week ago with putting out flowers. My sweet peppers are about the same. It's been a cooler summer than past years and frequent overcast and rainy days seems more than average. I think these plants will pump out blooms and peppers in Aug-Sept and be ready for an October harvest. In past years I could harvest peppers mid July through October and into November as long as a frost did not hit them.