My bearded dragon will only poop outside

So my bearded dragon, Marty, decided this summer he is only going to poop outside. He won't poop in his terrain, he won't poop in warm water, but as soon as I take him outside he will relax, jump I'm the grass and poop. This week I didn't really take him outside until today, he went almost two weeks without pooping because he wanted outside and due to my work schedule and the bad weather when I'm off I didn't have time to get him outside. He will literally paw at my door or windows after he's done outside wanting back in like a dog or cat (while I'm in a lawn chair outside watching him) so he can proceed to sit on his throne (the living room chair lol). Anyways I'm worried about how I'm going to go about this when winter comes, is their anything that will stimulate outside for him for the winter days so he can poop the way he wants to poop? I don't think he can hold it in all winter but I can see him trying lol. He's about 2 years old, I use reptile carpet in his terrain, his hot side temp is about 101, his cool side stays about 77-86, the humidity is 30, he eats dubia roaches every other day, he stopped touching vegis (he gets them every day still but they seem to be uneaten) about a month ago, all he really wants is blueberries and dubia roaches that I gut load.

Maybe try putting some fake grass in his terrarium? Or possibly, if it doesn't raise the humidity too much, plant a little tray of grass in habitat

I would do the fake grass, but set it up near the exit door, that way you can still get him use to pooping outside his cage, which simplifies cleaning and sterility.

You could also try putting him on a routine that will work in the winter. Keep him in a room that has an easy to clean floor and just sit with him at around the same time every day until he goes (within reason). Maybe set up a portable basking lamp for him and give him breakfast (that's what I do). After a while he will likely get into the routine and figure out that he needs to go in order to "open" the door and go explore for the day.

I will try the fake grass at the door, I'm not sure I want to teach him how to poop on the floor, him going outside and pooping is actually really nice I'm just super worried about winter months when it's cold since reptiles can't regulate their body temperatures.

My aunt had a dragon who would only poo outside. He would even go out in the winter in the snow. He scratched at the sliding glass door until you opened it, he would run out fast, poo then run right back in. Of course if it was super cold, he wouldn't be allowed outside and would eventually go someplace else.

That gives me peice of mind, I'm hoping marty will go I'm the winter without being outside, I can't believe her dragon attempted to go outside in the snow! I guess if he holds it in too long I'll let him run outside this winter.

how cold will it be getting by the way? if it is a matter of snowfall then yeah drastic tempt drop to body could possible induce shock of some sort, but if its' just chilly then i dont think that'll be a problem. If you have or can manage a small scale heat light for outside you can use that on a patch of grass and have that as his charging station while he spends time outside... ???

It's missouri so the weathers bipolar. A charging stations not a bad idea