I live in Baltimore City. And recently I've been wanting to grow Georgia collard greens what is the latest date I want to start collard greens. From seed to ground in Baltimore City?
I highly recommend our color-coded planting calendar, available on our Home and Garden Information Center website here: https://extension.umd.edu/hgic/topics/crops
According to that calendar, collard seeds should ideally be planted between early June and early July. Collard transplants should ideally be planted between early July and early August.
We are approaching the average date of first frost in Maryland, so it's a little late to be planting even cool-season crops like collards. However, if you have quick-growing seeds like spinach or arugula, you could gamble on a late fall and plant them anyway, especially with row cover at night to protect them from light frosts. The risk is that they might be killed by frost before they grow large enough to eat. The choice is yours.