2 gallon containers can grow a much better plant than a 1 gallon. Morning sun is appreciated. Wilting is common and expected on hot days. If the soil is moist, they snap back once things are a bit cooler. Magnesium or Sulfur deficiency improved by the addition of Magnesium Sulfate.
Sulfur is usually the culprit.
Soil tests should indicate what problem exists. Our grower Christine says that if micronutrients are not a problem after testing, then suspect the inability of the roots to uptake nutrients. Damage to the roothairs by overfertilizing or drought can cause a chlorotic condition. Leaching with clear water and attention to good watering practices should reverse the situation. Too much fertilizer will kill them.