Is it a chem mix or a organic mix? I wouldn't suggest mixing chem ferts cause that could cause some serious burns if done in excess (which it usually is). You could mix organic ferts but look at the N-P-K value and make sure you are mixing the right nuts for the time of growth in the plants life and not giving it too much P when it needs N. Quick question; 1) What is the N-P-K value of the ferts you are planing to use? This info will help determine your answere partly.

Another thing, did you add any bone meal or other types of soil enhancments to you soil (I'm assuming your using soil). If you did then the plants can usually can last a month or longer without needing any ferts. Also, it is really recommended that you don't give your plants ferts during the first month of their life. Hope some of this helped.

Happy Toking :rasta: