You're growing in Soil if the diary i looked at is this crop. Soil isn't the same as coco. It hangs onto nutrients way longer than coco does. If you are feeding weekly 900 to 1000 ppm in soil you are over feeding them and they are gonna burn. In soil it's feed, water, water, water repeat regiment. Not feed, water, feed, water or feed, feed, feed.
Feed, Water, Water, Water, Repeat.
And you better figure out what the pH is in your soil if you aren't managing it cuz i'll bet it's high.