Two issues with most green houses is moisture control and CO2 content. Moisture needs are usually 50-60%RH to avoid fungus growths. Higher CO2 levels help plants to grow. Outdoor levels are 450-500 ppm. Low air change rates cause low CO2 levels inside the green house because plants consume CO2 and produce O2. Beyond this, go to ASHRAE for specific recommendations. Medic weed is grown in green houses. There are recommendation on ventilation and humidity control. Dehumidification with fresh air ventilation is common with commercial growers. Plenty of info available on web.
Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
Use +Merv 10 air filter. -Don't forget the "Golden Rule"