He doesn't need any greens or veggies at his age, as Knobbys said if he eats them it's simply a bonus! And fruit should only be an occasional treat, a couple times a week at most, too much sugar for him.
Beardies typically don't eat many, if any greens/veggies until they are at least over a year old, and there's a reason for this: Bearded Dragons grow and develop from hatching to 2 years of age, BUT THEY DO 90% OF THEIR GROWING DURING THEIR FIRST YEAR! SO THEY NEED TONS AND TONS OF LIVE, GUT-LOADED INSECTS EVERY SINGLE DAY OF THEIR FIRST YEAR OR MORE OF LIFE! And although you should offer him a salad of healthy greens and veggies every day, you should not give them to him until AFTER HE EATS HIS LIVE INSECTS!!! At his age greens/veggies are simply a bonus and not a real part of his daily diet! He will not grow to his full potential or develop properly, and can develop Nutritional Deficiencies if he isn't getting at least 90% of his diet in live insect protein up until he's a year old...
So you need to stop focusing on getting him to eat greens and veggies, and start focusing on making sure he gets at least 2 live insect feeding sessions every single day up until he's at least a year old. Each live insect feeding session should last for 10-15 minutes, and he needs to be allowed to eat AS MANY LIVE INSECTS AS HE WANTS TO in that 10-15 minutes! So be sure his UVB and basking lights have been on for at least 1-2 hours in the morning, then give him his morning live insect feeding session, feeding him as many live insects as he wants in the 10-15 minutes, and do the same in the late afternoon or early evening, being sure to allow him to be under his lights for at least 1-2 hours AFTER his last feeding session of the day. It's best if you order your live insects in bulk online if you don't already, you'll save a fortune, and he'll start eating a ton of them if he's not being filled up with greens, veggies, and fruit. Only offer him a small salad of healthy greens and veggies AFTER he eats his first live feeding session of each day, you cannot let him fill up on greens and fruit (again, fruit should only be once or twice a week in a couple small pieces, too much sugar and no Nutritional value to him) before he eats a large feeding session of live insects.
You're doing him a much better service to simply gut-load his live insects right before he eats them with the healthy greens and veggies that you've been trying to get him to eat. A bearded dragon's diet must be 90% live insect protein and 10% greens/veggies until they reach a year to a year and a half old, this is the point when most of their growth and development is done. Then their diet usually naturally switches to eventually 80% greens and veggies and 20% live insect protein at 2 years of age and thereafter. But what you're doing now will only result in stunted growth, nutritional deficiencies, and developmental issues.