These plants have been grown by us in the usual way, in sterile culture and then introduced to potting compost. But we have started a rather interesting way of doing this. We keep a sample of soil with the appropriate symbiotic fungus labelled and ready to use. Actually, when I say a sample I really mean a lot, enough to do a lot of potting from. When the stock starts to run down it can be replenished with a suitable potting compost and mixed in, whereupon the fungus populates the entire mixture. This seems to introduce a symbiotic fungus which will invade the adult plant, or at least be available in the close vicinity for seeds to get started.
This approach seems to work well and we haven't had any failures yet. However, we are about to try this on a 3.5 acre south facing site on very light sandstone derived soil. This is very poor soil which drains almost like a colander, so it is something of a risk putting these orchids in. We shall see if the idea works in principle quite quickly as the healthy plants should put out their over-wintering leaves towards the end of the year. If they don't we will be surprised, but more than that, rather disappointed because the next step would be the introduction of Bee orchids to go with them.