I have several large 5+ft Australian tree ferns that I bought at Home Depot last fall. I bought then for $18 for 5 gallon and they are the largest ones I ever seen sold. However, I am having a huge problem with all of them. The fronds keep on drying up and shribbling for no apparent reason. Today I just counted 4 fronds and yesterday those exact fronds were lush and healthy. And the new fronds unfurling now unfurl but before unfurling all the way they dry out and turn brown, leaving only a few of the leaflets to unfurl at he base. Not sure what is going on but I'm in San Francisco and these should thrive fine. The mature larger fronds that dry out are not drying because of old age because some are newer growth while older fronds seem healthy. I keep the soil moist but not wet and there is slight wind but nothing terrible. They're in the shade and with some other Australian tree ferns I bought at the same time that are thriving really well in the same conditions so I'm not exactly sure what's going on. These healthy ones I bought from HD as well and in the same size pot, they're just a little smaller at 3' but have beautiful green fronds and healthy new growth. I'm think the larger ones are still adjusting to shock or still hardening off but it doesn't make sense that the smaller ones bought at the same time are doing excellent. Any advice???