Growing at school was fun… 😊
You must know that Pro mix soil is already pre-fertilized. It’s good enough to last about 3,4, weeks depending on the pot size. Adding nutrients in week 2 wasn’t the best thing to do.
What’s happening now is the EC ( Electrical Conductivity ) level of the soil is too high.
Nutrients are minerals, those minerals turns into Sodium Chloride ( NaCl, table salt ) when they’re not used entirely by the plant. The soil turns into an hypertonic environment where the fluids gets sucked out of the plants because of the osmotic pressure in the roots zone.
My best advice is to get an EC/TDS meter to control the Electrical Conductivity and Total Dissolved Solids of your feeding solution and soil.
After watering, you just need to take a sample from the drain to analyze it and check the EC levels.
At this stage of the growth, your plants should be fed only with bio stimulants like Humic Fulvic and amino acids, with some enzymes to boost the microorganisms in the soil and roots development.
You’re supposed to feed only when the nutrients in the soil starts to get used up, around beginning of the fourth week at 600 ppm on the TDS scale of your meter.
Don’t follow blindly nutrients manufacturers feeding schedule, they’re built to make you use more and make you re supply faster.
Growing Cannabis is easy despite there’s a deep science and requires years of studies, just follow the 3 main rules, not too much light, not too many nutrients, with the right amount of water.