My large blue/puple iris rhizomes are now almost fully exposed over ground. I noticed last year that they didn’t bloom well and subsequent greenery didn’t seem to last. Should I cover them completely with soil?
These sound like german irises which like to have the rhizomes at soil level, but they do tire over the years and are usually lifted, the ground dug with plenty of compost and re-planted, in July after flowering. Or you could simply scatter some well rotted compost over the root area to give them a boost.