Seed slot

A Seed Slot is where you put plant seeds in. At the beginning of the game, you have 6 slots and you can buy more from Crazy Dave's Twiddydinkies. They are unlocked in order, and the next one is unlocked immedately after the last one was purchased. For the 7th slot, since it is unlocked before the shop is unlocked, Crazy Dave asks you to buy it once you get $750.

Extra Seed Slots

 * 7 Seed Slots: $750
 * 8 Seed Slots: $5000
 * 9 Seed Slots: $20000
 * 10 Seed Slots: $80000 (not available in some versions)

Trivia

 * Early in the game, when you have less plants than slots there is no seed selection screen.