Everybody is trying to start seeds in their window right now and I would like to address this with a few pictures, and a few short words.
Growing plants in the window isn't the best idea. This is because there isn't enough light, and the windowsill is a very cold place at night.
Here are some pictures of plants growing near a window. Notice how much the plants are growing towards the light. This is what is called a leggy plant. Notice also that the plants have very thin stems, which means they are weak.
Weak plants are difficult to transplant, because you have to be ultra careful when handling. Plus, the plants won't be strong enough to withstand any environmental assaults. If you don't have access to some grow lights, then a better tactic would be to germinate the seeds indoors where it is warm, then grow them outside under cover of a coldframe, plastic tunnel, cloche, or some other protection with access to real sunlight. Bring them inside each night to keep them warm. They will grow slower during cool spring days, but the plants will be much heartier.