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