This very large species, which incidentally smells like fox pee should never be grown under the shade of trees, any trees as they are best grown, like so much else by mimicking as far as possible their natural habitat. As with their close relative Frit. eduardii these two species grown on open unforested mountainsides from the eastern most parts of Kurdistan - straddling Iraq, Turkey and Iran, across Iran non desert regions and as far as Afghanistan, they are also reported from the very western end of the Himalaya including Indian and Pakistani controlled Kashmir. The soil absolutely must be free draining not just inclined that way with a pH neither to high nor too low. I suspect the plants of both species which we grown here are at the most northern limit for success, circa 58 degrees north. They do not "do" high rainfall areas or grown in which water might lay for however short a period. ideally if in doubt make sure the ground is sloping to avoid any risk of waterlogging and rot which follows. One of the major mistakes is to constantly work from splitting bulbs rather than renewing stock by seed. As with lilies once infected by whatever this just keeps getting passed on and around. I get a feeling from this thread some folk may be working with infected stock and are therefore on a hiding to nothing. Sow the seed, plant out the resulting bubs on clean ground, things should improve providing the other issues are dealt with. I also believe depth of planted bulbs is another important issue, they need, here at least, to be down at around 20 cms. Neither species is a woodland plant, certainly not from climates affected by oceanic influences, I really struggle with them but they do work for me, they are as hard as nails and here in northern Scotland our crude USDA hardiness equivalent might be circa 6. Frit. eduardii is by far the most beautiful to my eyes and also the easiest with lovely big chunky bulbs which even I can't kill. When splitting them I use a sharp knife cut across the base plate and produce four out from one, best done in the autumn. Over fed bulbs succumb to infections very quickly, these frits need to be grown hard and dry. Mine are growing in pure glaciated sand and gravel with a pH of 4.5 but they can take upto around 6.0 or so I am told. The also get a top dressing of well rotted leaf mould, 10 cms thick mostly birch, alder and oak but others no doubt would be OK too. They work on a short temperature heat sum gradient of 8 C x a relatively few days of 8 C to initiate onset of growth therefore it is important to guard against late frosts, I use a fleece if I think we might get a hard one and all of them are on a north facing slope to help guard against that. I haven't so far worked out the heat sum of 8 degrees C x X days @ 8 C as I am preoccupied with doing so for Lilium right now but my impression is that it is not a large number. Maybe some day when time allows if I haven't lost the plot before hand. I hope this helps, Iain