We use greenhouses primarily to regulate the environment inside, creating conditions suitable for plant growth most or all of the year. However, greenhouses are still subject to weather conditions and daily and seasonal changes in temperature, light, and other environmental parameters.
Although we can temper some of these changes by cooling and heating systems, supplemental lighting, shade curtains, etc., conditions are still not controlled in a predictable and consistent manner. As a result, there are still differences in greenhouse crops produced from one location to another, from one month to the next.