My veggie plants are a little yellow and crispy around the edges. They get watered one to two times a day. The soil stays fairly moist, so I don't know if it is caused from over watering or something else.
Yellow and Crispy Around the Edges of Veggie Leaves
Certified GKH Gardening Expert
They may not be getting watered deep enough. If they are in containers, make sure to water until the water comes out the bottom. If they are in the ground, water 1-2 times a week for 20-30 minutes or until your watering system has put 2" of water onto the soil.