Uli: It is interesting that you mention using horse manure as part of a potting mix. However, I think that you need to mention that it needs to be composted and cannot be added "fresh" because it may release too many nutrients too quickly and burn plants. I find horse manure a WONDERFUL addition to all sorts of potting mixes....especially terrestrial orchid mixes. Although it seems counterintuitive, composted horse manure is relatively inert and it does not engender growth of fungus or bacteria that would be deleterious to the geophyte. (At least not in my experience). Also, it functions as a slow-release fertilizer to the plant. I got the idea to use horse manure a few years back when I read about an orchid grower who used only 100% composted horse manure as a medium to grow Disa. For those of you who don't know, Disa is a genus of African orchids that are very difficult (almost impossible) to grow ex-situ because they are very sensitive to pH, dissolved salts and impurities in water. I figured that if fussy Disa orchids can be grown beautifully in horse manure then perhaps it would be interesting to experiment with using horse manure with other terrestrial orchids. I use a mixture of 25% composted horse manure, 25% mulched oak leaves and 50% sand to grow my terrestrial orchids and it gives terrific results with Bletia, Funkiella, Dichromanthus, Schiedeella, and Sarcoglottis. Uli, you mention that the potting medium you use is "too fine for orchids", but the potting mix you describe (without perlite or the amendment of commercial growing mix) would work for some epiphytic orchids in the Catasetinae tribe. (e.g. Catasetum, Mormodes, and Clowesia). This potting mixture placed in an open basket would be excellent for potting a vigorously growing Catasetum. I use pure horse manure to grow my Catasetums and it does the trick. > > Dear All, > > > Sorry to be so late in answering to questions! I grow Hippeatrum aulicum > in an open compost made of shredded wood composted with grass clippings > and horse manure. This wonderful compost is mixed with perlite and > commercial potting compost.It works wonders on epiphytic cacti and also > on the two epiphytic Hippeastrum species, H.calyptratum the other. I saw > them in nature growin on moss covered tree trunks where the large fleshy > root system formed extensive thick structured along the trunk. This > compost is too fine for orchids, except terrestial ones and > unfortunately tends to decompose further. > > Greetings from cold and frosty Germany, Uli > > >