This is the 2nd year of attempted greenhouse planting/harvesting. However, my problem is having such small yields. I have drip system set for 2 minite watering every other day. My plants are in 2' X 2' diameter barrels. Am I watering too often or too long at a time?
Lack of Product Produced
I feel the only way to determine whether or not a plant is getting enough moisture is to check the soil. If the soil is moist to the touch, don't water. If the soil feels dry, water till it runs out the bottom. If you are giving only 2 minutes of water every other day to a 2'x2' container in a greenhouse, the plants should be dry. Since you don't state your location or zone, I'm assuming you are in the US. If so, during the summer, doesn't it get awfully hot in the greenhouse?
Your lack of yield could be simply lack of pollination. Especially in a greenhouse. This article explains: https://www.gardeningknowhow.com/garden-how-to/beneficial/insect-pollination-process.htm