I was one of those that stopped by but didn't comment. And the reason I didn't comment was because I was short on time and I think there is a lot to say here. I want to encourage you to do some reading and studying if you are serious about cultivation of cannabis. Hushpuppy is correct when he says that it is not a weed and it does not grow like one. The more you know, the better your chances of success. You are going to need a special place to put your plant that you can control the environment.
First we generally start seeds in a small container or something like a rapid rooter or rockwool cube so we can control the moisture to the seed and seedling once it sprouts. Seeds should be started in a seed starter mix. Seed starter mix will have no nutrients in it whatsoever and you do not want anything that controls moisture either--those moisture crystals are not good for growing cannabis, which needs wet and dry periods. I am with Hushpuppy in that I believe that the soil you have planted in does not look good. It has big chunks of bark and does not appear to have any perlite or similar to help aerate the soil and aid drainage. I suspect that the soil is contributing to yellowing of the cotyledons--not good when the plant is this young.
You should also plant at least 3 seeds. Males are worthless except for pollen. They are generally destroyed as soon as they show themselves. So, to get 1 healthy female, I would plant at least 3-4 seeds. If these are bagseed and you have more, you may want to start over in a better soil or a starter plug and a smaller pot. What are your temperatures and is there a light over the seedling? If so, what?
