If you don’t have a growlog please answer these questions.
What strain are you growing? Is it Auto, Fem or Reg?
Are you growing Indoor or outdoor?
Are you using nutrients? Which ones? How much?
Growlog link: [paste your link here]
Were the seed germinating for too long and you have a large tail?
Either that or you placed the light too close to the plant and you’re stunning its growth. How far are the lights?