Tips for propagating this genus are available in William Cullina's book Native Trees, Shrubs & Vines: A Guide to Using, Growing, and Propagating North American Woody Plants (c) 2002. In it he mentions collecting seed prior to when it drops to avoid squirrel pilfering, and picks pods when their husks turn yellow in late summer but before they have cracked open. Let the pods dry just enough to crack and then plant the seeds outdoors or store them in damp vermiculite in the 'fridge for the winter. (Sown outdoors, they might be eaten by mice and other wildlife unless protected.) This genus is intolerant of desiccation in storage/dormancy and must also experience stratification (cold exposure) to germinate. Often, this means exposure to about 40 degrees F for a period of three to four-and-a-half months; in this case, while remaining slightly damp but not so wet that they begin to mold.

Cullina also notes that "seed production, especially on bottlebrush buckeye, is very inconsistent." This means that pods may not all contain viable seeds. For some species, seeds that float are non-viable and seeds that sink are viable, but we do not know if that is the case with Aesculus; you may have to experiment and try several.

Miri

Thank you. I've picked a bunch and as soon as I see cracks in the pods, I'll plant.

You're welcome.