Kentucky Coffee Tree Seedlings - September 2021

Earlier this Spring, I came across some Kentucky Coffee Tree seed pods at a park by Downers Grove South and began the journey of getting them to sprout and grow into tiny tree seedlings.  I posted about that process (cracking up the pods, soaking the seeds, planting them, etc) back in June here. Over the past 70 days, I've kept them alive in their little nursery stock containers and have watered them (enough) to get the little trees to grow.  In the photo above, you can see my tray of little Kentucky Coffee Trees.  And one little Maple seedling.  

In total, there are five containers of Kentucky Coffee tree seedlings with to little trees in each one - ten total trees.  (And that one Maple). 

Below, is a look at one of the containers showing the pair of seedlings.  As a milestone, the trunks of these are NOW woody.  No longer green - or red like the leaflets.  If you look closely, you'll see that the trunk has a TINY bit of 'turned wood' on it - near the top.  Meaning, the woody part that will remain after the leaflets drop isn't just a straight stick in the air.  

Here, below, is a pair of Kentucky Coffee tree seedlings from a different angle.

And, finally...below is a photo of just that lone Maple tree seedling.  This one was a tiny seedling that had self-sown in one of our beds, so I dug it up and stuck it in the pot.  

As the temperatures begin to drop, I have to (now) start thinking about overwintering these seedlings.  Where do I put them?  Bring them in the garage? Screened porch? Dig them in the ground?  Leave them in their pots and just assume they'll be fine?  I've read conflicting advice - but this response from the Toronto Master Gardeners regarding Catalpa tree seedlings (another native tree), seems like the right answer:

The seedlings can also be overwintered by planting each of them a sturdy plastic pot in the ground. This should be done a week or so before the expected first frost of the late fall or winter. The pot should be placed in a sheltered position. Place it in a hole that is slightly deeper than the container. Put gravel in the hole which will help with drainage in the spring. The rim of the pot should be slightly lower than the ground. Back fill around the pot and then put some soil over the top of the pot. You can put a little mulch over this but don’t let it touch the plant. In the spring as soon as the ground has thawed, lift the pot out of the ground. When fresh growth starts you can plant it in its permanent location. They can also be placed in cool space indoors where the temperatures are in upper 30’s or lower 40’s. Give the plants just a little water a few times over winter to keep the roots from getting too dry. Since you have several seedlings you can try each of the methods to find out which works the best.

(emphasis, mine) 

Don't do the same thing with ALL of them.  I'll dig a few in the ground and mulch them in.  Then, I'll put some in the garage.  Some in the screened porch.  Hopefully all routes lead to leafing out trees next year.  By then, hopefully they'll be ready to plant in the ground.