Could you change the amount of time plants take to grow to be mature? I think it would be cool if extremely rare plants could take a long time to grow and common plants could only take a few minutes.

i am having a wee bit of a problem with plant tycoon.my supply seeds are not refilling in 24 hrs. sometimes takes up to 36. i have not played with the time. also does anybody have any charts that i can print out. do not have access to google docs

There are a lot of good breeding guides in the Plant Tycoon Guides in our forums (click Forum List and scroll down - below the games section).

You don't necessarily have to have "played with the time" to have a problem with the game's timers. Many people have accidentally changed the system clock, or Windows has done it for them to correct a drifting system clock.

How often do seeds become available in supplies?

The Supply Shop gets new seeds approximately every 24 hours of "real" time (according to your computer's system clock).