Often called boosters or fortifiers, these products are designed to be used in addition to a base nutrient. They are heavily concentrated in potassium and phosphorus to give plants the extra boost needed to create increased flower sights during the bloom stages of growth and to generate robust flowers and increased essential oils. A lot of base nutrients will have a higher NPK than others and claim to be heavily concentrated than competitors. We have found that ones that add a fortifier or booster to the product line are designed to maximize the timing that plants need nutrients most and not waste nutrients when they are not needed. Look for products that suggest using on specified weeks of the bloom period and have high concentrations for the boost your plants will need then.
Our experience has found DNF Bloom Fortifier 0-50-30 to utilize this technique best. Look to buy it online here:
Or buy directly from the manufacturers at Homegrown Hydroponics Inc.