It sounds like your on the right track--the heat/sun does a lot of stimulating with appetite so it's best to keep them warm. But make sure they have access to shade/cooler spots as well. I keep my basting area for my 1 year old when he's not outside between 92-95 degrees.

I picked up a food scale at the grocery store a few months ago and weigh/measure my torts (especially my 1 year old) on a regular basis..keep track.

Grazing on grass, weeds, clovers, and edible flowers is ok all the time..just don't let them get to spoiled on salad mixtures. I had a hard time weaning my 1 year from salad mixtures since I thought that was the best way to go--it wasn't.

Since than, I've started with Mazuri and they love it. I was told to feed a hatchling tort 1-2 pellets a day, soak it in water, it turns to mush pretty quick. Dust with calcium/vitamins a few times a week (very little)...and just make sure the little guy is gaining weight..you should be okay.