i believe that the growth buds are in the main stem, so although you could root a leaf, it will not grow into a complete plant. the usual way to propagate heuchera is through division.

Making More Plants says Heuchera can be propagated by leaf petiole cuttings.

Hello......from Michigan...bought one (Heuchera..Purple Palace)....I love it....when to divide....spring? ....I LOVE THE COLOR.....Thanks .....gert

I've had good luck with one I bought recently - Heuchera 'Key Lime Pie' - a gorgeous chartreuse. I loosened the soil away from the crown and pulled off small divisions right at the crown (they didn't have any roots attached) - actually the correct term would be basal cuttings, I guess. Anyway, I trimmed each cutting down to just a couple of the smaller, new leaves. I stuck them just deep enough to stand up in a peat:perlite mix and rooted them under intermittent mist, though you could probably use a plastic cover in the shade - anything to keep them moist. Mine took about 3 weeks to root - I got eleven out of the twelve I stuck. I will plant them out in the garden next spring. The mother plant has now grown back to about the same size it was before I took the cuttings, so am going to do some more.

Heuchera Palace Purple is one that will come true from seed - you might try collecting seed.

where would you find the seed on this plant? MariLynn

Heuchera should be devided frequently, or not at all. If left for 3 years, the main stem can become woody, making division much more dificult and success less likely. If you divide them every spring, you will have the most success. IMHO.

In spring cut off the tall stalk that shoots up & replant in soft soil, keep moist, & sprouts into it's own plant. As long as it has some stem & the pink shoots showing new sprouting leaves it works. Did this first with Palace Purple then with Firefly. Next spring I'll do it with Caramel.