Yellow buckeye question

[StevenBiars]

I was given a sack full of yellow buckeyes by a friend last fall. I put them in the bottom of my refrigerator over the winter and sprouted them. After they sprouted, I planted all of them in small pots and placed them outside. For the most part, the summer heat roasted them, and despite my best efforts, I was left with about 30 trees out of the 100 or so that I potted that I was unable to give away. The some of the leaves on the remaining trees developed some spotting (I assumed it might be a blight), and the leaves died off. I assumed all of the trees were dead, but just this week I noticed that each of the remaining trees has developed a bud-like formation (seen here: View attachment 204530 )at the top. These look to be more woody than leaf-like.

Any suggestions on how I can save these trees would be greatly appreciated!