All three provide measured feeding, with a mix of nutrients to help grow healthy plants, abundant vegetables and spectacular blooms. The difference lies in how the different forms work and how often you use them.
With continuous-release plant foods nutrients are “coated” with a thin permeable membrane that allows either one or all of the nutrients to be metered out into the soil in a controlled manner. These generally only need to be used every 3-4 months during the growing season.
With water-soluble plant foods the nutrients are immediately available to plants since they are delivered two ways, through the roots and through the leaves. These plant foods are mixed with water when you are ready to use them. For best results, use a water soluble plant food every 7 to 14 days during the growing season.
Like water-soluble plant foods, liquid plant food make nutrients immediately available to plants through the roots. However, liquid plant foods generally come pre-mixed, so you just pour them onto the soil. Liquid plant foods are also recommended for use every 7-14 days.