The reason I suggested to winter the Trident forest in the shop is because there is NO TIME for them to develop maximum cold hardiness. Kansas would be pushing the limit for cold hardiness for trident. You might be just barely inside their tolerance range, you might be just a touch too cold in winter. Regardless, these came from Brussel's in Mississippi, where the weather would be very summer like right now compared to your climate.
IT takes about 2 full months, 8 to 12 weeks of slowly decreasing night time temperatures for a tree to make the metabolic changes needed to have maximum winter hardiness. The metabolic changes include increasing sugar content of the sap, lowering the amount of water stored in cells, changes in the growing ends (meristematic tissues) of roots and buds, and many more changes I can't think of. Key is it takes time to adapt to cold. For example, we own a blueberry farm. Blueberry flower buds form in August. Normally the buds are freeze hardy through -16 F, if they are allowed the time to adapt. So -16 F (-27 C) is no problem if it occurs in January after a "normal" steadily declining night time temperature autumn and winter. When a January thaw hit in 2013, after 5 days with highs above 50 F (10 C) one day got to 80 F (26 C) then a return to normal winter. Only hit zero F, (-17 C) and nearly 100% of the flower buds were killed. No harvest that summer.
My concern is the trident forest has not had time to adapt to Kansas cold. Outdoors you will get too cold too quickly. If you had purchased the forest in June or July, I would have no concern about adapting to cold. Then you only would be facing the issue of whether tridents are good through your area. Also, the shallow ceramic pot is likely to get broken by freezing and thawing. So the pot, and not enough time to adapt are why I recommend wintering in the shop.
In my area, tridents are problematic, they have proven sensitive to my extreme cold winters without extra protection. When I winter them in the well house, there is a period, which begins about a month before it is safe to put them outside where the well house warms with the warming of the ground, as temperature creeps to 40 F, then 42 F, the Japanese maples and trident maples break dormancy about 2 to 4 weeks early. Then I either have to do the "in and out" dance, and risk frost or freeze if I don't get them back inside on a cold night, or I have a months worth of weak, etiolated, growth that has to be removed when I put them out for good in spring. Either way, breaking dormancy too early is either a back ache or a set back because growth has to be removed. In the ground, or on the ground, for me, Japanese maples and tridents survive 2 or 3 out of 5 winters. Sometimes they make it, but by the 5th year one winter has killed them. Same issue with Japanese black pine.
By the way, JBP need heat to really wake up in spring, so storing in the well house for winter is not an issue. THey stay dormant through 45 F, and are still dormant when it is safe to put them out in spring. For whatever it is worth
