When the percentage of germination is required to be shown, the label shall show the month and year in which the germination test was completed. No more than 5 calendar months shall have elapsed between the last day of the month in which the germination test was completed and the date of transportation or delivery for transportation in interstate commerce, except for seed in hermetically sealed containers in which case no more than 24 calendar months shall have elapsed between the last day of the month in which the germination test was completed prior to packaging and the date of transportation or delivery for transportation in interstate commerce.