Humboldts Secret Best Flowering Plant Food Flower Stacker - Let Your Flowers Mature To Their Maximum Potential (128 Ounce) FLOWER STACKER WILL assist in the development, maturation, and ripening of your flowers. START USING FLOWER STACKER after week 3 of flower at a rate between 1-8ml/gallon. VERY CONCENTRATED - Use at a rate of 1-8ml/gallon. Be careful of plant burn. 1ml  20ppms. START WITH A low rate and Increase it gradually. COMPATIBLE WITH ALL MEDIUMS. Yes, but as Flower Stacker is <span class="a-text-bold">very concentrated</span> be careful of plant burn. 1ml raises PPM&#039;s by 20. Flower Sacker contains<span class="a-text-bold"> Phosphate, Soluble Potash, </span>and <span class="a-text-bold">Vitamin B-1</span> FlowerStacker is great for any plant you want to have <span class="a-text-bold">bigger better flowers/fruits.</span> Flower Stacker can be used between <span class="a-text-bold">1-3 times a week</span> depending on the strength and how well your plants are responding. A good refence is that 5ml =1tsp, so <span class="a-text-bold">1ml is 1/5 of a tsp</span>.