Types of Fertilizer for African Violets

Water-Soluble

• Water-soluble fertilizers are crystalline salts that easily dissolve in water and come in different formulas. For African violets to bloom well, the phosphorus rating -- the second number in the three-number code -- must be higher than the nitrogen rating. Water-soluble fertilizers usually do not contain trace elements or micronutrients. Fertilizers that are 100 percent water soluble are recommended for African violets because they are absorbed readily and do not cause root burn. Water-soluble fertilizer should be applied regularly, but in small doses. A common practice is to use 25 percent of the solution at each watering, rather than the recommended amount, once a month.

Liquid

• Liquid fertilizers can be organic or inorganic and are diluted before applying. Inorganic forms are synthetic and made from chemicals. Organic solutions, such as fish emulsion, are derived from plant or animal by-products. They not only contain the basic macronutrients, N-P-K, they contain valuable micronutrients such as iron, zinc, manganese and others. If you use synthetic fertilizers regularly, apply an organic liquid fertilizer occasionally to supplement chemical fertilizing.

Granular

• Granular fertilizers also contain the essential nutrients and come in various proportions. You can mix them into the soil when planting or you can work them into the top layer of soil. Watering can cause the nutrients to leach through the soil. The nutrients release quickly. Granular fertilizers are the least expensive option, but read the label to make sure that the nitrogen component is not urea based, which is not good for African violet roots, especially in granular form. Another way to utilize granular fertilizers is to add specialized components at planting time. For example, adding bone meal, rock phosphate or super-phosphate to the soil at planting time is an effective way to provide extra phosphorus to aid in blooming.

Slow-Release

• Slow-release fertilizers typically release nutrients over three to four months, depending on conditions. They come in the form of coated pellets or soil spikes. They are synthetic and usually do not contain trace elements so they should be supplemented with organic fertilizer occasionally. Because these fertilizers are slow-release, there is little risk of root burn. They are easy to use and you can add them to the potting soil at planting time or to the top of the soil anytime. The fertilizer ratio should contain a high phosphorus content to suit African violets.