My chicks are 7 weeks old now - they have been in the coop and run for over 2 weeks - at this point can I give them greens from the garden? - so far they have only been given non medicated starter/grower feed
You can try. They may or may not eat them. Some people on here seem to get upset about that or feel that their chicks are weird if they don't immediately scarf down any new foods. Sometimes they go crazy over new stuff, sometimes even grown chickens won't touch it, even if it is something many people give as treats. I sometimes toss my adults cabbage leaves from the garden. They might eat them, they might ignore them. They tend to like kale better. If I leave it alone they will often eat cabbage though, just not always immediately.
Have your chicks had access to grit? Some people buy chick grit but mine get it by pecking it from dirt. If yours have access to the ground you will probably see them pecking at the ground. They are picking up small gravel to help them grind food in their gizzard. Before they get green stuff from the garden or anything that they need to grind up they should have grit.
A story. When I harvested corn from the garden to can, I gathered a small yogurt cup full or corn ear worms. I dumped those worms on the ground around a bunch of 10-week-old chicks that had been free ranging for a few weeks. A couple of the bolder cockerels tried to to sneak up on that pike of caterpillars. Slowly and cautiously inched forward. A caterpillar wriggled! Run away! Run away!
Slowly and cautiously they started back, really on high alert. A caterpillar wriggled! Run away! Run away! This repeated four or five times before a cockerel finally got close enough to grab one. Within a few seconds that stack was gone, gobbled down. This is the kind of stuff that makes chicken TV better than anything on cable, satellite, or network.
Don't be shocked if they don't immediately try the greens. It might work better if you chop them up or even puree them. But I'd just toss them the leaves and let them figure it out. Eventually they will.