The "South Harbor", early spring ruby watermelon are a key crop of Zhangpu town, with a total planting area of 2650 acres (1 Chinese acre=666.67 m2 ), producing 5100 kilograms per acre. The watermelons were certified pollution-free agricultural products in 2003, and also named one of Suzhou City Famous Brand Name in 2007.

The early spring ruby watermelon grows from the end of January to the beginning of February, and is ready for sale in early May. It is an oval fruit, with a relatively thin skin and ruby red color flesh, weighs about 1.5 - 2.5 kg, and has a diuretic, effect.