The Kernel. . You must first buy the seventh ($), eighth ($), and ninth ($20,) seed slots. Still requires 10 seed slots. They have different designs in each game. At the beginning of the game. Seed slots represent the number of seed packets the player can bring into a level. The Wall-nuts and (non-gold) magnets are ditched, replaced with relatively inexpensive Kernel-Pults in Pumpkins. As per the Plants vs zombies wiki: Extra Seed Slot ten - $80, (unavailable on iOS, Mobiles with Samsung bada OS, DS, and Android because. To get the 10 slots in Plants vs Zombies, you gotta hustle a bit! First off, keep progressing through the Adventure mode. All together, it costs $, to get all 10 seed slots.