Thanks for writing. It really depends on how much space you have and what your needs are.
For the average person or family, one or two tomato plants may do it because they can bear about 10 pounds of tomatoes over the course of the season. But something like carrots, on the other hand, you only harvest once --- so you'll need to determine how many carrots you'll want in order to know how many to plant.
If you need some help getting started in knowing what to plant where, try our free vegetable garden plans!
---Justin, Senior Garden Editor, BHG.com