There are a lot of theories as to why watermelons have stripes. The most common one is actually wrong! Some people believe that the number of stripes on a watermelon indicates ripeness, this is sadly not true. The reason that watermelons have stripes is to show when they are ready for harvest. However, the number of lines does not matter. The color in between the stripes should be a light green. There are even some varieties of watermelon that do not have stripes!