Hi, Ellis ...
It's really hard to answer your question without more information.
1. Soil or hydro?
2. If soil, what is your mix?
3. If soil, what fertilizers are you using? How often do you use them and ... how often do you water? Do you have a moisture meter?
4. If hydro, do you have an RO unit? What nutes are you using?
5. How much light and what type are you using.
6. What are the temps in your grow space?
Vi