Don't know abt House and Garden, but for mj I use this chart as a starting point and adjust as needed, smoe strains can take higher and some lower, I'd imagine it works for any fertilizer....hope this helps.
PPM for Hanna Chart PPM
Seedlings, Early Sprouts ..100 to 250
Early Vegging ......................300 to 400
Full Vegetation ....................450 to 700
Early Blooming ...................750 to 950
Full Mature Blooms ...........1000 to 1600