There are many vendors represented at the greenmarket in Union Square. After having made several visits checking out the plants and prices, I have found vendors who offer quality plants for the price. On a recent visit, I went to Nature's Healing Farm and Binder Farm.
Nature's Healing Farm has great deals on their starter herbs like the $2 4" herb pots, which also offered at 3 for $5; that's a great deal! I picked out pineapple mint, mint, (2) Italian basil, and (2) Thai basil. They were the ideal size for me because these herbs will get fuller and taller. Plus, mint is a very prolific herb so a little mint plant will eventually get you lots of mint. Probably, more than you'll ever use.
They're at Union Square usually on Wednesdays, Fridays, and Saturdays. Their location changes but they can be found along Union Square East either near 16th Street or at the north corner across from Starbucks.
Binder Farm sells quality starter plants and herbs, in my opinion. Their prices are also good. You get a deal when you buy certain quantity like 4 or 6. For instance, I bought six (6) starter herbs, which included chives, cilantro, thyme, lemon thyme, trailing rosemary, and chervil. I also picked up hot pepper plants like cayenne and jalapeño, and two strawberry plants for a total of four (4) starter plant packs.The only reason I picked up another strawberry plant is because the flowers from these plants are pink!
The people at Binder Farm are nice especially the elderly lady. She's friendly and helpful! The young man who rings up the plants is also helpful and accommodating. When I asked if he could put my plants in a box, he obliged and cut up a large plastic bag to make it easier for me to carry.