The majority of California commercial production occurs in the San Joaquin Valley. Over the past ten years, pomegranate production has increased by more than five times. In 2011, 113,535 tons of pomegranate were produced with a total market value of almost $100,000,000 (NASS 2012). However, pomegranate acreage declined in 2012-2013 due to low market prices. Despite a brief decline in acreage in 2012-2103, production and market value are expected to continue increasing with the growing popularity of pomegranate as a highly nutritional fruit (Hummer et al. 2012).
Pomegranates (Punica granatum L.) are one of two species in the Punicaceae family cultivated commercially. The most common cultivars grown in California are Wonderful (main season crop), Granada and Foothill (early season crop). These cultivars have been selected based on consumer preference for high sugar to high acid ratios, and dark red rinds and arils (Day and Wilkins 2011). Although the three common commercial cultivars are very similar, there is a wide range of rind color (light pink to dark red, yellow, orange, green and black), seed hardness (hard to very soft), aril color (dark red to light pink, yellow to almost clear), seed quantity (up to 1300 seeds per fruit, Stover and Mercure 2007) and sugar/acid balance (very tart to balanced sub-acid) available among pomegranate cultivars. Variation among selected fruit bearing and ornamental cultivars is described in the Pomegranate Cultivar Yable within our website (LINK ).
Pomegranate cultivars are either fruit-bearing or ornamental. Ornamental cultivars produce large, showy male or intermediate flowers, ranging in color from red, orange, pink, white and combinations of red and white. They produce mostly inedible fruit. Fruit bearing cultivars tend to be less showy and produce male and hermaphroditic flowers which produce edible fruit of varying size (Özgüven et al. 2012). Both types of trees can either be self-pollinated or cross-pollinated by insects or hummingbirds (Tous and Ferguson 1996). The timing of pollination is important because the stigma is only receptive for 2 to 3 days before quickly declining (Stover and Mercure 2007). The amount of pollination determines how many seeds form within the fruit, and ultimately, fruit size (Hartmann et al. 1997).
Post flowering, pomegranates require 6 to 7 months to ripen (Stover and Mercure 2007). Fruit is typically ready to harvest between August and November in California. The pomegranate rind can begin to crack open as it ripens, reducing postharvest quality and lifespan. To combat cracking growers have tried harvesting fruit early. However, because pomegranates do not continue their ripening process off the tree, it is best to keep the fruit on the tree longer to obtain an optimal flavor (Tous and Ferguson 1996).
Pomegranates are subtropical fruits, but can acclimate to Mediterranean and humid tropical climates (Stover and Mercure 2007). It has been recorded that pomegranates can withstand freezes from -9°C to -12°C (Westwood 1993). However, they need a long, hot growing season to properly mature, which is what makes the San Joaquin Valley ideal for pomegranate production. Pomegranate grows best in deep loam soils, although it can tolerate a wide range of soil types, including moderately saline soils (Stover and Mercure 2007). Fruit quality declines when trees are grown in highly alkaline soils and soils with poor drainage. Pomegranate trees can survive drought conditions, but fruit quality and quantity decline without sufficient irrigation (LaRue 1980). Adequate soil moisture is necessary during tree establishment (Stover and Mercure 2007), and should be maintained at the same rate, especially close to harvest, to minimize fruit splitting (LaRue 1980). During maturation, both irregular irrigation and extreme rain can lead to fruit splitting (Hepaksoy 2000).