Looks like indica? IIRC, Herar is a hybrid but I see fat leaves...
Usually, when this plant will yellows at this stage it needs a touch of cal mag. Also, check PH of any and all watering, nutes, etc. If the PH is not right, plant will suffer so ( I only count on distilled water to be neutral and still measure it) your plant cannot absorb nutes, even though they are in rich soil. Certain PH will cause lock out of certain nutes, so always PH (6-7 or so...I like 6.3 b/c sometime when using up, it gets difficult to get higher without significant adding of UP.) always PH your fluids carefully. Any additives whether cal mag or other nutrient WILL alter PH, which will need adjusted with UP/DOWN.
PH meter + plus cal mag + UP/DOWN set and all will be well.
Bubba