These values are 1.5 and 2 times higher than that of marigold flowers. However, the potassium requirement of marigold flowers is 3.5 times more than that of microalgae (0.012 kg/kg microalgae powder). The water demands of marigold flowers and microalgae are 1–1.6 and 0.19–0.77 kg/kg dry mass, respectively. Assuming available lutein content is 20 g/kg dry in petal powder and 5 g/kg in dry microalgae powder, the annual production rates of lutein are 120 kg/hectare for marigold flowers and 350–750 kg/hectare for microalgae. The lutein production rate is 3–6 times higher for microalgae than for marigold flowers, mainly because microalgae (unicells) grow much faster than marigold flowers (higher plants). Marigold flowers need land and labor for cultivation, while microalgae need energy and are device-dependent. A common misconception is that microalgae consume more water than marigold flowers; that is, the water needed to produce 1 kg dry microalgae powder is 2–10 times less than needed by marigold flowers (Table 2). The microalgae process consumes more energy than that for marigold flowers. Acien et al. (2012) demonstrated that the equipment and its depreciation account for the lion’s share of microalgae cultivation cost. Assessing basic demands and choosing suitable equipment are very important tasks.