Hi Lisa,
It is never too late to plant greens, you should plant some every 2 weeks all summer so you always have a fresh supply coming on. Since you are putting them in containers, move them into shade to protect them from the afternoon sun during the hottest part of the day, or put them in a place they will get dappled sun, and make sure they get plenty of water. Peas do like it cool, but again if you can get the out of the sun during the hottest parts of the day you might be able to get them to produce.

-Rosalinda