What is the best fertilizer to use on orchids?

Orchids require regular fertilization to grow and flower properly, but too much fertilizer can damage them. The best types of fertilizers for orchids are water-soluble types of fertilizer and they are easy to use. Orchids growing in barks of trees require a fertilizer with a higher content of nitrogen, such as 30-10-10 or 15-5-5. Mounted orchids and potted orchids grow well with even fertilizer ratios, such as 20-20-20. During autumn, a "bloom-booster" type formula can be used which has a higher phosphorus content such as 10-30-20.

Use soluble fertilizers once a month and a dilute fertilizer solution can be used to water plants weekly during the growing season. Each month, plain water should be used to rinse any accumulated fertilizer salts out of the pot. When the foliage growth stops after flowering, reduce fertilizer applications until new leaf production starts again.

The nitrogen source is an important consideration in selecting the base for the fertilizer. The term "base" is used because it may be necessary to use other components to create a better balance of nutrients. Among different organic sources of nitrogen, feather meal works well with orchids. Feather meal decomposes slowly and thus provides a long lasting source.

Most forms of phosphorus are harmful to beneficial microbes. The molecular relationship of di-calcium phosphate seems to be of the harmless form and di-calcium phosphate is also the form used for orchids. It comes in granulated form that can be mixed into the feather meal base.

The third important nutrient content is potash. Potash is highly soluble but a vital component that easily seeps out of solid fertilizer applications before the other components are used. Liquid sources of potash can be sprayed in the form of potash soaps. Greensand is mined from sea beds and provides potash and just about every micronutrient.

Fertilizers are generally rated by the amount of the three "NPK" components. The NPK ratio is a reflection of what is immediately available to the plant. Chemical fertilizers or inorganics are potent and of high value and they do provide high quantities of the three basic components because they are soluble salts. With organics much is not immediately available to the orchids.