If they are in pots, lift the pot and get to know what it feels like when the compost is wet and dry. Never leave the pot sitting in water in a saucer. Use a soil based compost ( John Innes no 2) not soggy peat based.

Also only water from the bottom.

If you think that they might want watering, leave them for another day or two before you do it.

There speaks a man who avoids watering at all costs :-)

...unless you forget to come back in a day or two!!

He has just been chastised for having left 5 pots of aubretia, 2 of saxifrages and 1 of campanula in full sun - unwatered - for over 2 weeks! They are now watered and we will get them into the ground on Sunday.