Dragon not pooping - how long is too long?

I have a male bearded dragon that is about 2 years old, adopted from a rescue. I just got him about 2 months ago. I'm concerned because he hasn't pooped in about 3.5 weeks. He eats mostly veggies (collards, mustard greens, cilantro, butternut squash). I give him medium dubias twice a week dusted in calcium. He is on tile in a 75 gal glass tank, with temp range from 75-95F (measured with digital IR thermometer). I have a reptisun 10.0 HO, a halogen flood, and a ceramic heat emitter. All lights turn off at night except the ceramic heat emitter. He really dislikes baths (frantically scrambles to get out the whole time), but I have been trying to give him a bath about once a week in warm water and rub his belly when I do. Before this, he was pooping about every 2 weeks. I can't feel any hard lumps in his stomach, but his belly is starting to look pretty full. I got him to take a couple droplets of olive oil yesterday, but still nothing's happened. He isn't eating many of his veggies, but a couple days ago when I fed dubias he ate about 15, and otherwise seems to be acting normal - he basks, he walks around some, he looks alert, he even eats a few pieces of veggie. He's also shedding right now, I don't know if that has anything to do with it. What else can I do? Is it time to go to a vet?

It sounds like he's OK based on his behavior and if 2 weeks is normal for him then 3.5 isn't awful. Hopefully the olive oil will help. If he doesn't like baths don't offer them. It's good to keep him well hydrated though so try dripping water on his nose with a plastic syringe or dropper and see if he'll lick that up. If he doesn't go in the next couple of days try a few more drops of olive oil.

My male beardie has gone 8 weeks between poo’s befor now. He much prefers to stay in the middle to cool side of his tank which stays about 80. He is very lazy but def not over weight. If he goes to long I have him running round the room for a bit. He hates baths too.

Dragon2016, your Beardie sounds like mine, won’t poop in his tank, goes a long time not going. Does not like baths either, but he’s getting one tomorrow. Got to mark that on the calendar, lol.
I use Repashy grub pie mixed with some unsweetened applesauce and baby food prune & a few drops of olive oil & some running around. He’s hiding under his side board where his tank is on. He did get some good sun outside today.

I know! My diary makes very strange reading too “big poo today yay!” I have to and my girl came from a breeder and she poo’s eats and sheds really well, my boy from pets at home is a nightmare. I was just looking and the last time he shed his body was last year in the summer! Genetic or earlie care?