Be useful to know what plants you're talking about, but in general, most plants are happy in peat based compost. Browning round the edges usually means underwatering, but some plants that don't like sun or wind may do this, hard to say without knowing which plants they are.

I agree with what Bamboo said. Peat is a growing medium that does not provide any nutrients to the plant. There has been a move towards peat-free compost over the past couple of decades as peat is considered un-environmentally friendly. Removal of peat from peat bogs causes a lowering of the local water table, which causes drying of the surrounding bog, which in turn causes decomposition, resulting in the release of greenhouse gasses, which are a contributing factor to global warming. Best not to use peat-based products in my opinion.