How can the gardener determine whether the plant is homozygous or heterozygous for the allele that determines seed texture?

User's comment: Since the Smooth texture is the dominate gene no matter what the out come is going to be a smooth pea plant. The gardener could go back and make a punnet square with the smooth gene and wrinkled. I guess it just depends on what the parents traits were to determine whether its homozygous or heterozygous.