I purchased BioAdvanced All in one Rose and Flower Care Concentrate.  (Systemic/drench)

The instructions state 

>Roses: 2 fl.oz in 1 quart of water treats 1 plant.

I have hybrid tea roses that are 1' tall x 1' wide and English roses that are 6' tall and 6' wide.

For other shrubs they state to use 1 fl oz to 1 quart of water per foot of plant height.

I am fairly sure that 1 quart of diluted mix will not adequately treat the largest rose bush, but I also don't want to use too much and harm the plants.

Anyone have knowledge on how much is appropriate based on size of a rose bush?