From Pat Hudnall,
You may divide a Platycerium when the offsets "pups" have at least 2 fronds. It is best done in the spring or summer when the sterile "shield" fronds are brown. Obtain a rectangular piece of cedar at least 10" wide 12" tall. Drive 10ea 1.5" galv nails in a 10" circle in the middle of the board. Tie the end of a 6 piece of 20lb fishing line onto one of the nails. Twist an eye screw at a 45 deg. angle into the back of the board near the top. Soak about ¼ cuft of uncut sphagnum moss in water. Thoroughly water the stag to be divided. Using a sharp knife cut through the sterile fronds to the board at an equal distance between the parent plant and the pup. Slide your knife along the board, like youÂd filet a fish and remove the pup. Take the pup, place it in the middle of the circle of nails on the board. Make sure the pup is oriented (up) the same as it was on the parent plant. Squeeze most of the water out of the moss and pack it around the pup. Using the fishing line, cross back and forth tightly over the shield on the pup, close to the fronds, hooking the line around the nails. When it is securely fastened tie the end onto one of the nails. Using the technique described above apply a "patch" of moss into the area where you removed the pup from the parent plant.

Hi Pat, Thanks for your input on dividing the Staghorn fern. The "cage" it was in had rusted through and it wound up on the ground. I'm sure I'll be able to get at least 12 beautiful plants from the parent. I'm sure with your advise these should "take" without any problems. Regards, Keith

I bought three plants from 3" pots from a garden center as they were on sale... I tried dividing two of them, and all of the halves died, except for the one intact plant. I could either have overwatered it or something because the leaves of the divided plants were "health" looking until i pulled them out of the new pot a month later to see the rooball totally rot out.
Maybe i divided them too early?

Yeah whyang, you probably divided them too early. It can be done when they're that small but you have to be pretty good and careful.