Whether you grow vegetable plants directly in the soil or in containers, you must thin them to allow for adequate root growth and plant spacing. Although some gardeners resist the idea of voluntarily pulling healthy seedlings from the soil, if you do not thin vegetables, you will not reap a large and bountiful harvest. Keep a close eye on seedlings as they sprout in containers so you can thin them before they become overcrowded.
Water the soil in the planting container thoroughly and evenly. Moist soil will make it easy to pull the seedlings from the soil without disturbing the surrounding seedlings. Allow the water to soak into the soil for 15 to 30 minutes before you thin the plants.
Remove any seedlings that appear weak and unhealthy first. Pull the seedlings out of the soil with your fingers or clip them off at soil level with pruning shears or scissors.
Pull up additional seedlings until the plants are spaced between 6 and 8 inches apart. Consult the specific planting instructions for spacing recommendations if you are unsure of proper plant spacing for your vegetable plants.