The seeds transported on their own would begin to germinate during the long voyage to India. The terrariums allowed the seeds to start sprouting and growing in a healthier environment than in the ships holds.
I grew up on kraft yellow cheese slices as well, my parents could've afforded better cheese however I think its more to the availability (much like the OP states) of better quality items. Grocery stores in America (well big cities at least) have changed massively in the past 30 years, and once you have some decent cheese, you wont buy single slices again.