Trying to introduce new veggies

I have a roughly 3-4 month male beardie, not sure of his age exactly, he's from a pet store. He's about 10 inches and 40 grams last time I checked.

He gets a mix of dubia roaches, phoenix worms, and crickets daily. I really wanted to at least introduce him to veggies, see if he would try them. I don't think he was ever fed veggies even by his breeder, and he had no interest in them at the store. I keep getting told by people that he needs to at least try them at this age. I finally managed to get him to eat something veggie two days ago, which was kale. He loves it, I give him a few bites dusted with calcium after the bugs and he goes nuts for it. Is there any other kind of veggie that might be enticing enough to get him to try it?

In the past I tried collard greens, blueberries, grated carrots, and bell peppers, none of which he'd try. If I did manage to get him to get a bite, he'd spit it out. Any other suggestions?

Here's a good list you could try.
http://www.beautifuldragons.com/Nutrition.html

Turnip greens and mustard greens are also very good for them as well as collard. Spaghetti squash is also very good. You can just break it up and give him some, it's high in calcium and fiber. Here's a list of some foods you should take a look at, the ones in green are good for staples and black are occasional.

http://www.beautifuldragons.com/Nutrition.html

Looks like Terry15 and I are on the same page