To know if you can leave them out in the winter we need to know your location. They are totally hardy in the ground but the roots could be damaged if the pots freeze for a long period. They would be happier and easier to care for if they were in the ground. Again, your location affects when you should plant. In my climate you could plant throughout winter. But that's not the case if you have cold winters and frozen ground.

I am mid michigan - zone 6a according to an online planting zone map for mid-michigan (saginaw/bay areea)

Wait for them to lose their leaves to plant, or do it now, making sure to correct any root circling and roughing up the outside of the soil ball to help roots grow outward. These ways you don't have to worry about what to do over the winter.

plant after Labor Day

I'd be inclined to put them in the ground now if you can keep them well watered, depending on a number of factors. Since they've been kept in partial shade, the foliage may be sensitive to full sun conditions, so you might want to transition them gradually. What is the planting site like? Does it have some protection, or is it fully exposed to the elements? Ideally your soil is well drained but also retains enough moisture that it doesn't dry out too badly through the summer. Do you have any idea why the previous tree didn't survive? Your location isn't very far outside tuliptree's native range, so they should survive given the right conditions. Another consideration is where you obtained them? Southern provenance tuliptrees may be iffy in our climate, at least until well established.

I plan on putting them in the back yard in an area that receives AM sun and shade in the afternoons. protected well on the E, W, and S. North isn't too bad. Soil drains very well. I believe the other one didn't survive because 1, I think I over watered, and 2, I think when I transplanted it, I did it too deep. when I got that tree from Arbor Day Foundation, it came to me broken in 1/2. I pruned it and planted it anyway and it thrived all that summer. the next spring and first part of the next summer it thrived then slowly turned yellow. I obtained these ones off amazon - a nursery - I believe from KY but not 100% sure on location. Our neighbor across the street had one that was VERY mature and well established - he had it cut down - no idea as to why.

here is a link to my previous tulip tree issues: tulip tree

plant them when the leaves start turning color in your area...

see link section 1.. for timing... mid august is NEVER planting time .. imo .. but im not aware of northern and southern TPs ....

https://sites.google.com/site/tnarboretum/Home/planting-a-tree-or-shrub

also note.. no amending the planting hole

after the leaves turn color and fall off... the tree will have many months to grow roots to settle in..and get established in 3 to 5 years ... all winter if your ground doesnt freeze ...

there are extremely hardy and fast growing in my part of MI... there is no reason for you to be treating them like babies...

seems to me.. i went to a bay city lumber baron B&B and the parlor was paneled in tulip poplar... so he must have been harvesting them in your general area ....

ken

Should be fine to plant them now in the Saginaw area. If regular watering could be a problem, consider using a granular water-holding polymer product when planting.

Getting roots established before hard freezes should be a plus in ensuring survival.

I'll put my 2 cents in here too.

I'm assuming you put them into the pots this spring.

But either way, wait until the trees start shutting down for the season, as already mentioned.

Then when you're ready, prepare the planting site with a hole as recommended in kens link.

Being these are small seedlings, tip the tree out of the pot and put the root ball into a pail of water large enough to let it soak for a while, then tenderly finger work the soil out and bare root the tree right in the pail, keeping it wet.

I don't know if my link has the best instructions for planting, but it does have good diagrams of how to set the bare root tree on a mound created/piled/packed in the middle of the hole and divide the roots out evenly in radial direction away from the trunk.

https://www.gardeners.com/how-to/planting-bare-root/8764.html

Then back filled remembering not to let the roots be exposed to the sun for very long or dry out at all.

IME: It's good to have a little extra soil on hand, to make sure you get the tree backfilled at the proper depth (root flare at grade level). I always seem to run out of soil when doing this.

Then, put a grassless area and mulch layer around the tree a couple of feet out and check to make sure the soil doesn't dry out after planting, keeping it moist but not wet and muddy.

Also keep the wood mulch a few inches away from the trunk.

Roots will then continue to elongate until the ground is near freezing, for the rest of this season, helping the tree to start out next spring, partially established and ready to grow new roots.

Stake the trees if they seem unusually unstable or if in an open or windy location. Once the leaves are gone for the season, wind shouldn't be a problem and with small trees, they generally stabilize quickly by next spring.

Agree with rusty_blackhaw's comments above. Plant it now and keep it watered, and that will maximize root growth in its new location before winter. Mulch well and use deer protection if needed in your area. I've planted potted tuliptrees in late summer a number of times with good results.

' that will maximize root growth '

Isn't that a bit of a stretch dave?

When you consider that Fall root elongation doesn't begin until the formation of winter buds sends hormones to the roots, initiating the Fall growth.

In fact, I've moved trees too early in the summer and noticed transplant shock in the form of wilting and loosing leaves.

imo: Waiting until the tree goes dormant is superior to jumping the gun.

Thanks, dave,

That answers my question.

I always learn something from these discussions.

:-)

Tulip trees (Liriodendron tulipifera, Tulip Poplars) are beautiful trees, They are relatively fast growing, and end up being over 40' tall. We have several in our yard.

This is a new house cut into a wooded lot. 12 years ago when we moved here, the tulip trees were sort of telepole tree. After 12 years, the lower areas have grown branches and are becoming nicely shaped trees.

Don't forget the pretty yellow flowers in the spring.

PS: Has anyone else required to log in before posting? I do have had a user ID and password for years, but never had to log in again before posting