I grew pure haze three times and only the third time did I have completely healthy plants. This is what I learned:

Don't overwater - haze strains are sensitive to overwatering stress (water logged, root rot)

Don't over fertilize - I started with 1/8 strength tiger bloom and watched how the plants reacted

Check your PH - invest into a nice soil ph meter, I made sure the ph was within the correct range

Repot your plants into larger pots twice - once right before flowering and the second time in the middle of flowering. I know this sounds a little odd but after i repotted in the middle of flowering the bud production exploded. make sure it is good draining organic soil.

haze strains have the best highs in my oppinion. hope this helps your cousin.