Not every seed planted in the vegetable garden will germinate, which is the reason for sowing additional seeds when planting. Once the seedlings begin to grow, it is necessary to thin out the vegetable plants, so they aren't over-crowded. This will allow remaining plants the chance to reach their maximum potential. The task will not necessarily be performed all at one time, but at times appropriate for each of the garden vegetables. Thin vegetables when they are still small, before they begin competing for garden space. For root crops, thin before the taproots become fleshy.
Identify each seedling row in the garden. To perform the task accurately, you will need to know what type of vegetable it is, what height it must be for thinning and how close that type of vegetable should be to other plants.
Select the smallest, weakest plants for removal, leaving the healthiest and heartiest, spaced according to the recommended spacing for that vegetable type. Remove the seedlings by picking, as you would pluck a weed from the garden.
Reserve the picked vegetables that you can use, and discard the rest or use in the compost pile. Some vegetables, such as carrots, are tender and delicious when picked during thinning.