These tables will show you which crops are more profitable to use the seed maker on
Assumptions: The seedmaker gives on average two seeds for every one plant consumed. Green means you should use the seedmaker. You'll lose money by selling the harvest and buying new seeds. Yellow means it's a net zero profit if you use the seedmaker or sell the harvest and buy new seeds. Red means you should not use the seedmaker. You'll earn more money by selling the harvest and buying new seeds.
These rules don't hold up as well for plants that continue to produce after their first harvest.
(Increases sell price of crops by 10%) (All crops grow 10% faster)