JustAGirl
If you have the
seed packet there should be directions for thinning on the back of the package.
If you want only one plant you would keep the strongest looking
seedling and remove all the rest. If you want more than one plant transplant each
seedling to its own pot when the first set of true leaves appear. Much depends on the size of the container holding the
seeds.
As the sprouts grow they will develope two rounded
seed leaves. Next, two leaves (called true leaves) will appear above the round or
seed leaves. Plants can be moved to their own pots at that point. If you want only one plant then keep the strongest looking
seedling toward the middle of your planting container and cut off at the soil line all the other
seedlings.