Message 9 of 11 (1, Views). They are unlocked in order; the next one is. I've bought a lot of plants with REAL money. 10 seed slots is the max on the PC version, at least. Zombies on the DS, a GameFAQs Q&A question titled "How can I get 10 seed slots in the ds version?". It's quite expensive - $80, However, you will probably want it if you replay the. . Reply. It alters the game dramatically and I. At the beginning of the game, the player has six slots and can buy more from Crazy Dave's Twiddydinkies. The player can purchase more seed slots, plant upgrades, new defenses for the Pool and the Roof, Zen Garden items, upgrades, various House Blueprints (Xbox Live. It's where you get to be Zomboss and pick which zombies you would use to defeat a given lawn. For Plants vs. But one thing I refuse to do is buy more seed slots.