No it isnt, in chapter three, Yana will give a vegetable seed to the player after completing a quest, it should be planted on the main island immediately after its attained. When Yana gives the vegetable seed to the player, she also requests that the player delivers 1ton of vegetables to her Ark for further analysis of the radiation on the island. After planting the vegetables seeds, the player is able to grow vegetables on the main island. Im not sure if its even possible to obtain vegetables in any other way than this, or if its even possible to buy a vegetable seed from one of the NPCs :/.
To clarify, spices are grown where vegetables are grown. They share the same crop type/fertility.
WOW i feel so fucking stupid, I just got by with money trading it but the guy is Right if you have vegetables you can build spice farms LMFAO thanks Ubisoft.
Xavier