Unfortunately, you can't. There is no room for the 10th slot on the DS/DSi/3DS Touch Screen. In Crazy Dave's car I see the slot being sold for $80, but it has a sold out sign over it. As per the Plants vs zombies wiki: Extra Seed Slot ten - $80, (unavailable on iOS, Mobiles with Samsung bada OS, DS, and Android because. . 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. MegaSuperab - 11 years ago - report. Matching two of a plant on the slots awards one seed packet. When will I be able to purchase this? plants vs zombies facebook game. Postponing its activity is futile, as a horde of zombies will approach while the player hoards sun.