flowers will come off after pollination.sometimes they turn brown as they dry up. You'll know within a week or two if you have blueberry pollination as the tips where the flower blew off will turn blue and start to form berries.

The more blueberries you plant the better your pollination success will be granted there are a significant numbers of pollinators and the flowers don't get damaged by late frost. you can also plant things to encourage our pollinating friends to stay near your home. many people kill clovers and reseed with grass for a more attractive lawn but clovers are nitrogen fixers and all bees from honey to massion love the clover flowers. there are many other plants you can plant to attract pollinators and not all pollinators are bees they can be bats, birds, insects, and lizards just to name a few. many also eat plant eating bugs also, so it's a win win. Google has some great things you can read up on. I'd start with blueberry pollination New York

The thing I like about about a 50-50 sand and peat mix is the sand never breaks down and drainage is assured, but I'm guessing if pH is a huge issue, pure peat's lack of drainage may be an advantage- especially where there's not much rain during the growing season. You needn't add as much alkaline water to keep soil moist. Until I started reading about using pure peat for blueberries on this forum I'd never known you could use peat by itself as a suitable potting medium. It's hard enough to even get wet without a wetting agent. Last year we were discussing a southern grower's good results in pots and he put small plants in large pots with 50-50 ground pine bark and peat as I recall.

Without seeing the plants or the berries, it's a bit difficult to know exactly what's going on but I'd suspect some nutrient deficiency. Plants grown in containers need pretty routine fertilization as potting mix supplies virtually no nutrients. Not sure what the reasoning for the fish foliar spray is - plants absorb very few nutrients via the foliage and it's therefore not a very practical way to fertilize. With the frequency of watering necessary for containers through the heat of summer, fertilizing weekly with some sort of water soluble fert is recommended. For the blueberries, I'd go with something like Miracid (aka (Miracle Gro for Acid Lovers) at half strength every week (weekly, weakly :-)). Or my preference, DynaGro's GROW (7-9-5), which contains a wide range of trace minerals as well. And blueberries are full sun plants as well, so light conditions could also be slowing berry development.