Peat bogs are important wildlife habitats, formed over hundreds of years, and the extraction of peat for use in gardening has contributed hugely to their destruction. Peat often gets water logged and if it dries out, it can be hard to get it to hold moisture again so, for environmental and practical reasons, choose one of the many peat free alternatives instead. (From The Gardener’s Book).
Sadly, I only read this advice now, after I had bought three pots of green fittonias in peat based pots! One has dried out due to the awful heat now and I am just not able to revive the plant!