[4] As head of Burpee Seeds, he immediately began shifting the firm's focus from vegetables to flowers.

These programs were aimed at city folk, teaching them how to grow food during shortages by buying Burpee seeds.

This period also saw the development of Golden Gleam, a double nasturtium, the Big Boy tomato, the Ambrosia cantaloupe, and also new varieties of petunias and marigolds.

During the 1940s Burpee moved on to genetic engineering, altering flower chromosomes using the chemical colchicine extracted from crocus plants.

World War II meant more shortages and another opportunity to sell seeds in the Victory Gardens campaign.

By 1959 Burpee had grown his father's company into the largest seed catalog mail order house in the world with sales over $6 million, equal to $62,712,329 today.