Baby beardies should get insects over plants at this age. Once he gets to 9 months, start putting in my greens, but feed him insects too.
My daily diet:
5 crickets every 4 days
3 mealworms every 3
Lettuce and other greens in their for a week, then I put in fresh
~Mine is 19 Months old, so he should be eating 70% Greens, 30% bugs