I use dolomitic limestone dust ( magnesium carbonate), but yes. Reticulate Iris require the opposite of the conditions needed for Hippeastrum. They like low humidity, cold, wet roots in winter,(not waterlogged), and cold draughts. Sand, stone, clay, gravel or compost are good for growing them in, so long as there is air and food in it, and it so long as they do not dry out during their Winter growth. I suggest temperatures of 4C (39F) to 12C (56F) for their spring Spring growth. On 19 March 2016 at 22:41, penstemon <penstemon@q.com> wrote: > >They are also very sensitive to drought while in growth, and need > magnesium > and food. > Magnesium in the form of, say Epsom salts? > Miracle-Gro for Tomatoes, which is what I use for snowdrops, as the > foliage withers, has some magnesium, too. >