if when you fed your plants half strength for the first time was the first feeding the plants recieved then its quite possible you have nute burn.
work you way up from 1/4 strength nutes when feeding to allow the MJ plant to get accustomed to the food it has to uptake and increase the amount over time i.e. a week.
feed them 1/4 strength every 3rd watering. do that for 2 or 3 feedings then up it to half strength every 3rd watering.
from there feed it 2 or 3 feedings of half dose and up it a bit more and repeat until you achieve full strength.
hope this helps
DISCLAIMER:Photo's under this account are ficticious and do not really exist. All plants are fake, made of plastic, and only used for learning purposes; however, I do not encourage any one to learn about growing, smoke, or grow marijuana. Tennessee Greenery is not a U.S. based grow. That would just be down right illegal...