Hi Steph, Plants not only take fertilizers up through their roots, but can also absorb nutrients through the leaf. Foliar feeding feeds the tree incredibly fast, and it is not lilmited to synthetic fertilizers. You can also use manure teas or fish emulstion, both of which are organic fertilizers. With foliar feeding, it is just a matter of getting the fertilizer (synthetic or organic) on the leaves with a watering can, or a sprayer. When using synthetic chemicals like Miracid, or fish emulsion fertilizer as a foliar spray, cut the label's recommended rate for dilution in half, then apply. I always foliar feed my trees early in the morning or late in the evening. Do not spray during the heat of the day. Take care - Millet