I am a new greenhouse owner and have grown tomatoes, melons and
cucumbers in 12" pots. I have used Bowers Peat Free compost, and as it
dries out quickly, I have installed timed irrigation, gravity fed from
rainwater butts. Using a variety of methods from mini-drippers to
micro-soaker hose this has had limited success. The most successful is
a ring of micro-soaker hose round each pot, but even so, the Bowers
compost drains so freely that water is running out the bottom of the
pots before the compost is full soaked across its breadth. The water
just seems to take the path of least resistance straight downwards.

I have potted vines in John Innes compost watered by the same method
without any problems.

Has anyone any experience of other peat-free compost?
If the Bowers was mixed with loam based (J Innes) compost, would that
help?