He's really cute! There are a few things you can try that may help get him to eat his greens. First, offer him different greens and veggies until you find what he likes. Some of my beardies really like squash, and it's really good for them. I try to use a mix of different greens every week, depending on what I find at the grocery store. I usually rotate mustard greens, turnip greens, endive, and escarole, and sometimes mix in shredded squash or a little shredded carrot. Here's a really helpful site when it comes to making salads for him: http://www.beautifuldragons.com/Nutrition.html
You can also put bugs (phoenix worms/repti-worms, dubia, etc.) in his salad bowl, or make the greens "move" by wiggling them in front of him or stirring the greens in his salad bowl with your finger. Movement attracts their attention, so if you can make his salad move, he's more likely to try it.
My three girls will eat their salad nicely, even if they don't always finish it, but my boy is stubborn (and spoiled), and will only eat his greens if I hand feed them to himThe earlier you can get your boy eating his salad, the easier it will be as he gets older and needs to make the switch to more salad than bugs.
Hope that helps!