This article is about the biochemistry of sugar beets. For information on planting and harvesting them, see Sugar beet harvest. Sugar beet has a conical, white, fleshy root (a taproot) with a flat crown. The plant consists of the root and a rosette of leaves. Sugar is formed by photosynthesis in the leaves and is then stored in the root. The root of the beet contains 75% water, about 20% (or 18%) sugar, and 5% pulp.
Sugar beets grow exclusively in temperate climates between latitudes 35° and 55° N. The crop has a growing season of 100–130 days and reaches a height between thirty and forty centimeters as harvesting approaches. The leaves are trifoliate and alternate between upright (i.e., erect) and laying positions, although this characteristic is strongly influenced by the photoperiod during the growing season. The flowers are produced on a racemose inflorescence; white in sugar beet ("Beta vulgaris" var." altissima") and yellow or purple in Egyptian or bunching varieties ("Beta vulgaris" var. "cicla").
The two different sugar beets are cultivated using different planting techniques. Egyptian beets are seeded directly in fields, while sugar beet is replanted after harvesting by tillage. The process of separating the seed piece from the stem is called decortication. After planting, the beets are thinned to 10–15 cm between plants.
The area in which they are grown differs both regionally and nationally, depending on climate conditions and the availability of irrigation water. The largest production areas lie in the vicinity of river basins with a moderate supply of water, western France, Western Siberia, Southwestern Australia, Spain, North Africa, and the United States.
Global sugar production has increased over time because of greater mechanization and innovations in farming. Between 1840 and 1975, for example, sugarcane growth increased by 250 percent worldwide; sugar beet growth increased by 600 percent between 1930 and 1990. As a percentage of total calories consumed, individuals in Western Europe, Australia, and the United States consume only about 6–7% of their daily caloric intake in sugars. As a proportion of monetary expenditure on food, individuals in Japan spend over 20% of their income on sugar.
Sugar beets require well-drained soil for successful growth. Planting is usually done in early spring when the temperature is above 10 °C and the soil moisture is adequate, but not excessive. In the United States, planting takes place from January to late March or early April. The seed is sown by placing it into a furrow about two inches (5 cm) deep that has been walked over so that the soil compacts slightly; leaving about 6 inches between seed furrows. Planting is done in rows about 16-19 inches apart. The seeds are 2 mm or 3 to 5 grams each, depending on the desired size of the beet, and are distributed through a hopper-like device that mixes the sugar beet with sand and drops it onto the prepared soil surface.