Deeeeeep corms. Hard to know which ones will bloom reliably. They transplant fine though.

The corms are very deep, 6 to 10 inches deep. It is difficult to dig them while in bloom as you usually break the very thin stalk connecting the corm to the leaves which kills the plant.

Mark the location of dense clumps in your garden, wait until the leaves disappear. Then use a deep shovel to dig up the clump in one piece about 12inches deep. Carefully break up the soil and separate the corms for trading.

usually break the very thin stalk connecting the corm to the leaves which kills the plant

Judy, you don't mean kills the plant, do you? I think you mean that you lose the foliage. The corm should be fine for the next year.

I find it best to dig them while they are first coming up - the link from foliage to corm is still relatively strong, it is only as the foliage ages that it weakens. But even when the foliage breaks off, I keep the corm and transplant it as intended.

Bottom line for me: if you get the corm, they transplant fine. I've seen some folks dig up a clump (on a rescue) and never even realize that they didn't get the corm. So I'm sure those folks think they don't transplant well!

If you break the stem before the leaves have had a chance to generate food for the corm, the corm will be weak and may not grow the next season.

But mostly I meant that if you don't get the corm, the leaves will die and not transplant.