By fall they had turned brown and then opened, dropping shiny brown nuts on the ground and leaving the dried split husk on the shrub.
Instead of waiting for suckers to fill in the empty area, why don't I just plant the abundance of buckeye nuts that have already fallen on the open dirt there?
I did some research and got conflicting info on how to plant buckeye nuts. The one area of agreement was regarding freshness -- the nuts need to be planted in the fall as soon as they drop and not be allowed to dry out. I'm good there. The dropped buckeyes from my shrubs look fresh and they don't appear dried out.
But the rest of the advice was a little confusing. Some said they must be scarified and planted in damp sand, others said they only sprout in year 2, not the first year after sowing. One source said all nuts germinated one year, no nuts germinated another year.
So. I dug holes in the empty spot in the hedge, I put the freshly dropped buckeyes into them. I did not scarify or soak or try to put them in damp sand. Just put them in holes and covered them up with dirt.
There were so many that I took a handful and potted them up in containers too. I'll keep the containers in the unheated garage, and keep them slightly damp all winter.
And then I took another handful and planted them under the trees in the forest on the back hill. I had done that last year too, but forgot where I planted them and never saw anything that looked like the big palmate leaves of an Aesculus seedling, so I assumed they never germinated.
Let's see next spring what comes up, either in the empty spot along the hedge, or in my containers, or on the back hill. In other years I have found volunteer buckeye seedlings coming up in my gardens, no doubt planted there by squirrels, so I know they will sprout.
Let's hope these sprout where I planted them.